US3959955A. Self cleaning rotary lawn mower blade and deck assembly. Google Patents
Publication number US3959955A US3959955A US05/571,490 US57149075A US3959955A US 3959955 A US3959955 A US 3959955A US 57149075 A US57149075 A US 57149075A US 3959955 A US3959955 A US 3959955A Authority US United States Prior art keywords blade deck shank mower pins Prior art date 1975-04-24 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Expired. Lifetime Application number US05/571,490 Inventor David M. Smith Frederick C. Mennen Original Assignee Smith David M Mennen Frederick C Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) 1975-04-24 Filing date 1975-04-24 Publication date 1976-06-01 1975-04-24 Application filed by Smith David M, Mennen Frederick C filed Critical Smith David M 1975-04-24 Priority to US05/571,490 priority Critical patent/US3959955A/en 1976-06-01 Application granted granted Critical 1976-06-01 Publication of US3959955A publication Critical patent/US3959955A/en 1993-06-01 Anticipated expiration legal-status Critical Status Expired. Lifetime legal-status Critical Current
Links
- 238000004140 cleaning Methods 0.000 title claims abstract description 18
- 210000001699 lower leg Anatomy 0.000 claims abstract description 70
- 229910052751 metal Inorganic materials 0.000 claims abstract description 26
- 239000002184 metal Substances 0.000 claims abstract description 24
- 240000000218 Cannabis sativa Species 0.000 claims description 8
- 230000004048 modification Effects 0.000 description 14
- 238000006011 modification reaction Methods 0.000 description 14
- 230000000712 assembly Effects 0.000 description 10
- 238000003466 welding Methods 0.000 description 8
- 239000004033 plastic Substances 0.000 description 6
- 238000007790 scraping Methods 0.000 description 6
- 208000002352 Blister Diseases 0.000 description 2
- 241001494496 Leersia Species 0.000 description 2
- 241001124569 Lycaenidae Species 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 239000000789 fastener Substances 0.000 description 2
- 230000001771 impaired Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
Images
Classifications
- A — HUMAN NECESSITIES
- A01 — AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D — HARVESTING; MOWING
- A01D34/00 — Mowers; Mowing apparatus of harvesters
- A01D34/001 — Accessories not otherwise provided for
- A01D34/003 — Means for cleaning the machine
- A — HUMAN NECESSITIES
- A01 — AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D — HARVESTING; MOWING
- A01D34/00 — Mowers; Mowing apparatus of harvesters
- A01D34/835 — Mowers; Mowing apparatus of harvesters specially adapted for particular purposes
- A01D34/84 — Mowers; Mowing apparatus of harvesters specially adapted for particular purposes for edges of lawns or fields, e.g. for mowing close to trees or walls
- A — HUMAN NECESSITIES
- A01 — AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D — HARVESTING; MOWING
- A01D2101/00 — Lawn-mowers
Abstract
A self cleaning rotary lawn mower blade and deck assembly in which the lawn mower blade is provided with metal pins symmetrically mounted on opposite sides of the opening for the center shaft, the tops of the pins being spaced from the deck by a critical distance of one-fourth of an inch or. 1/32 of an inch and being spaced from each other on from 2 to 4 inch centers, so that a 5 inch blade need only have four pins total, half on one side and half on the other side. The mounting of the pin is such that the pin shank whips through an angle of about 30°, e.g., about 15° each side of the normal vertical position and this whipping action which takes place during rotation of the blade removes debris, clippings, and the like which tend to adhere to the underside of the deck.
Description
The invention is in the field of motorized harvesters having the motor on a ground-supported carrier with a rotatable blade mounted on the motor shaft, and the motorized vehicles of this type are the common and widely used self-propelled lawn mowers in which a novel provision is made for removing debris and cut clippings which accumulate on the underside of the deck by means of flexible metal pin attachments secured in symmetrical fashion to the cutter blade about the motor shaft opening thereof and at a critical spacing from the deck. The invention includes novel attachment means for the pins to the cutter blade.
In the prior art the patent to Brown, U.S. Pat. No. 2,957,295, and the patent to Johnson, U.S. Pat. No. 3,396,518, each teaches the concept for cleaning cut grass from the underside of the housing of rotary mower by bringing a scraper into direct contact with the underside. The scraper is a second element mounted on a common shaft with the blade. If the housing is flat as shown in Johnson and Brown, then there is no problem with the scraper doing its job, but the housing in most commercial moweres are not flat. Instead, they are curved as shown in the patent to Phillips, Jr. et al, U.S. Pat. No. 2,953,888. It is an essential requirement in Brown that the Brown end elements 19, which are curved and act as air scoops to blow away the grass clippings out of the chute 22 at the top of the mower. This pair of upstanding metal elements 19, which are bolted or riveted to the ends of the blade 11, has as the only function an air pumping action, because of the inclined air deflecting surface at 13 (see column 3 of Browm, lines 5.- 18).
The significant difference of the present invention over Brown and Johnson is that a single blade is used instead of two blades. The separate blade for scraping the ceiling of the housing has never been used because most housings are curved and because when stones are picked up by the blade, they jam the cleaning blade.
There is no concept in these prior art patents for the mounting of non-cutting pins as well as non-scraping pins, which do not come into contact with the underside of the housing, but rather come into contact with clippings of grass or debris which cling to the underside of the housing.
There is further no teaching in the prior art of a further critical limitation that the tip of the flexibly mounted pin be spaced from the surface of the housing underside by 1/4 inch or. 1/16 inch and that a pair of equally spaced pins on each side of the center shaft mounting opening can completely prevent the building up of clippings or debris on the underside of the housing.
Accordingly, it is an object of the invention to provide flexible non-cutting and non-scraping pins on the rotary blade, which pins come into contact with clippings of grass and debris collecting on the underside of the housing by maintaining a critical spacing of about 1/4 inch from the tip to the underdeck and the thereby clean and prevent the buildup of clippings.
It is a further object of the invention to flexibly mount pins on the rotary lawn mower blade in spaced apart relation on opposite sides of the center of rotation, and with pins short of the underdeck by about 1/4 inch, so that the pins are dynamically balanced during rotation of the blade.
It is a further object of the invention to mount a plurality of pins on opposite sides of the center of rotation of the lawn mower blade but spaced apart to a degree of closeness (about 3 to 5 inch centers) as will keep the entire underdeck clean when swept by the flexible pins, which extend about 1/4 inch from the blade short of the underdeck.
It is still a further object of the invention to provide a mounting means for pins secured onto opposite sides of the center of rotation of the rotary mower blade which mounting means is flexible due to an elastomeric grommet which permits the end of the top which is about 1/4 inch short of the underdeck to whip and thereby clean underdeck from clippings.
It is a further object of the invention to provide a clip on mounting means for the above pins which does not require boring a hole in the rotary blade or fastening by welding.
The invention is a self cleaning rotary lawn mower blade and deck assembly comprising flexible mounting means, which secure metal pins to the blade, there being at least one pin on each side of the center hole of the blade in symmetrical mounting whereby the normal rotation of the blade during cutting is not impaired, the shank of the pin extending to a critical distance of one-fourth of an inch or. 1/32 of an inch from the underside of the deck so that the pin whips through an angle of about 15° on each side of the normal vertical position during rotation of the blade to remove debris, clippings, and the like which tend to adhere to the underside of the deck.
FIG. 1 is a top plan view of a power lawn mower fitted with a 24 inch rotary blade showing the spaced apart relationship of the symmetrically spaced flexible mounting means and pins on both sides of the center shaft bore and the upper deck;
FIG. 2 is a vertical section view showing the spacing of the flexible pins along the length of the rotary blade and the critical spacing between the top of the pin and the underside of the deck;
FIG. 3 is a view of a single pin mounted on the blade showing the critical spacing relationship between the top of the single pin and the underside of the deck;
FIG. 4 is a prospective view of the blade of FIG. 2, which is detached from the hub and shaft of the power lawn mower;
FIG. 5 is a fragmentary side view of an edger or trimmer showing a modification of only two flexible shank members on a small diameter blade;
FIG. 7 is a plan view of an alternate embodiment illustrating attachment of the flexible shank members by means of a strap to a cutter blade;
Mower Blade Bolt Stuck
FIG. 9 is a plan view of still another embodiment illustrating the flexible shank members assembled beneath the cutter blade; and,
FIG. 11 is an enlarged fragmentary vertical sectional view, similar to FIG. 8, showing another modification for mounting a pin shank housing on a mower blade; and,
The preferred embodiments illustrated in the drawings herein are directed to modifications, all of which provide pins symmetrically mounted on opposite sides of the center opening for the center shaft of the lawn mower blade in which the tops of the pins are spaced from the underside of the deck by a critical distance of about 1/4 inch and which are each mounted in a mower to permit the shank of the pin to whip through an angle of about 15° on each side of the normal vertical.
In the embodiments of FIGS. 1 to 3, the mounting means for the pins is welded to the blade above the blade, e.g., on the upper surface thereof. In the embodiments of FIG. 4, a larger blade is illustrated but with the same symmetry so that high speed rotation will not induce rocking of the blade. In FIGS. 5 and 6, an edge trimmer is shown with a very short blade but the same principle of symmetry of pin mounting is followed. In FIGS. 7 and 8, the attachment of the pin by means of a strap, this eliminating the need for welding. In FIGS. 9 and 10, mounting is started from the underside of the blade in contrast to the mounting in FIG. 1. In FIGS. 11 and 12, mounting is by means of a special hinged fastener means fitted with wing nuts.
As shown in FIGS. 1 to 3, the symmetrically mounted metal pins which are flexibly secured on each side of the center opening 9 of the blade 6 have a pin shank 1 which extends upwardly from the head 5. Each pin head 5 has its upper portion held within the metal cap 2 by means of a flexible rubber or plastic grommet 4 and the central opening of the grommet 4 is wider than the top opening 7 in cap 2 (see FIG. 3), thus permitting a whip action shown in deflection 8 in FIG. 2. The critical spacing of one-fouth of an inch from the top end of the pin shank 1 to the underside of the deck 11 insures that only the shank whips back and forth during rotation of the cutter blade (24 inch blade in FIGS. 1 to 4) at an angle of about 15° on each sde of the vertical, while the head 5 is securely held below rubber or plastic grommet 4 with the metal cap 2 welded securely to the blade 6 as shown by weld fillet.
The critical 1/4 inch spacing of the top of the shank 1 from the underside 11 of the deck is maintained for flat as well as curved protions of the deck so that pebbles or pieces of wood cut by the blade will be passed by the flexible shank. The spacing of the pins on about 4 inch centers provides balanced two pairs of pins on each side of the central opening 8 in a 24 inch blade.
This spacing of pins in an edger blade provides only one pin on each side of a small diameter 5 inch blade which in this case is on two inch diameters. The pin spacing is symmetrical in all installations whether on 2 inch centers about the center opening when in the 5 inch trimmer blade of FIG. 5 or on 4 inch centers in a 48 inch highway power mower blase as shown in FIG. 4.
The trimmer blade modification shown in the trimmer mower 22 of FIG. 5 can be seen in the profile in FIG. 7 and in side plan in FIG. 6. The same critical spacing of about 1/4 inch from the side deck 71 is shown in FIG. 6 as pointed out above in connection with FIGS. 1 to 3.
The edger trimmer 22 is of the conventional type and is provided with 5 inch blade 24 having mounting opening 28. The blade 24 has mounted thereon the flexing shank assembly 26 in the same metal cap as used in FIGS. 1 to 3 and utilizing the same flexible grommet as used in this first modification, whereby the whipping action of the shank about 15° inch on each side of the perpendicular line to the blade occurs due to the relatively large opening 28 in the cap of the shank assembly 20.
In FIGS. 7 and 8 there is shown still another modification of a mounting for the flexible shank units utilizing flexible shank assemblies 36, these comprising a strap 48, such as is commercially available from Signode Strap Company, the strap 48 surrounding flexible shank assembly 36 and the blade 34 so that the assembly 36 can be secured to the blade by straping instead of by welding.
The interior of the flexible mounting cap portion of the assembly 36 is in the same as in FIGS. 1 to 3 and FIG. 5, namely, a rubber grommet overlying the head portion 42 and shank 40 extending to within 1/4 inch of the underside of the deck while opening 46 in the cap 44 permits the whip action of shank 40, 15° on each side of the vertical, as in FIGS. 1 to 3 and in FIG. 5.
In FIGS. 9 and 10, there is shown still another embodiment of flexible mounting for the pins, which are critically spaced at about 1/4 inch from the underside of the deck, wherein the flexible shank assemblies 66 are mounted on the underside rather than the upper side of the blade. In this embodiment of blade 64 and flexible shank assemblies 66, the opening 76 in the rubber grommet 74 as well as the opening 68 in the blade are both larger than the shank diameter of shank 70 so that the metal cap 78, which is securely welded to the underside of the blade 64 as shown by fillet 79 bears directly against the head portion 72 of the flexible pin.
FIGS. 11 and 12 illustrate the modification for fastening the same flexible shank assemblies comprising pin shank 81 having the metal cap 82 capture or enclose the base of the shank 81 within the confines of the metal cap 82. A hinged fastening means 80 is formed from a sheet of rigid metal or plastic about each side of the hinge 85, so that the bottom strap portions 84 on each side of the hinge serve to come into face to face contact with the underside of the mower blade 6. Continuing from the bottom strap portions 84, the side straps 83 extend to the top of the cap 82 and are fastened on each side of the pin shank 81 by means of studs 86 welded to the cap 82, there being one stud on each side. The ends of the studs 86 are threaded, and each of the studs 86 extend through the cap to provide a bottom surface of the stud which bears againt the upper surface of the lawn mower blade 6 and which lies wholly within the cap 82.
Because of the bearing engagement of the studs 86 against the top of the blade 6 wholly within the cap 82, the circular bottom edge of the cap and the two shank bottoms of the studs provide secure strapping of the pins, which is maintained by the tightening of wing nuts 87 on the threaded upper ends of the studs 86. As shown in FIG. 11, the studs 86 are welded to the cap 82 to assure alignment and rigid fastening.
To dismantle the pin mounting the wing nuts 87 are unscrewed, the side strap portion 83 is lifted from the studs and the hinge 85 permits bending back the bottom portions 84 of the strap for simple removal.
Obviously, for certain uses where it is not desired to bore holes in the blade, the strapping arrangement of FIGS. 7 and 8 is preferred. In still other uses where welding machinery is available, the embodiments of FIGS. 1 to 3 may be preferred and in certain cases it may be desired to mount the flexible pin assemblies from the underside as in FIGS. 9 and 10.
Claims ( 6 )
A self cleaning power driven rotary lawn mower and deck assembly in which grass clippings and debris sticking to the underside of the deck assembly are removed solely by the rotating action of the lawn mower blade comprising:
metal pins each having a head and a shank projecting towards said deck mounted on opposite sides of the central opening which mounts the blade on the power motor of the mower to permit balanced rotation of said blade;
said flexible mounting means including a cap surrounding said head, an elastic grommet in said cap, and an opening permitting whip movement of the shank to about 15° on each side of the normal perpendicular extension of said shank; and,
the tip of said shank extending to about 1/4 inch from the underside of said deck whereby whipping movement at the shank ends removes the debris from the deck;
A mower blade and deck assembly as claimed in claim 1 wherein said flexible mounting means includes a strap which secures the cap to said blade.
A mower blade and deck assembly as claimed in claim 1 wherein said flexible mounting means includes a strap welded to said blade.
A mower blade and deck assembly as claimed in claim 3 wherein said cap is welded to the top of said blade.
A mower blade and deck assembly claimed in claim 3 wherein said cap is welded to the bottom of said blade and said blade is bored to permit said shank to extend from the underside of the blade through the top and towards the deck.
A mower blade and deck assembly as claimed in claim 3 wherein the deck is at the side and the mower is an edge trimmer.
US05/571,490 1975-04-24 1975-04-24 Self cleaning rotary lawn mower blade and deck assembly Expired. Lifetime US3959955A ( en )
Priority Applications (1)
| US05/571,490 US3959955A ( en ) | 1975-04-24 | 1975-04-24 | Self cleaning rotary lawn mower blade and deck assembly |
Applications Claiming Priority (1)
| US05/571,490 US3959955A ( en ) | 1975-04-24 | 1975-04-24 | Self cleaning rotary lawn mower blade and deck assembly |
Family Applications (1)
| US05/571,490 Expired. Lifetime US3959955A ( en ) | 1975-04-24 | 1975-04-24 | Self cleaning rotary lawn mower blade and deck assembly |
Cited By (12)
| US5491962A ( en ) | 1993-11-17 | 1996-02-20 | Trim-A-Lawn Corporation | Cutting head assembly |
| US5581987A ( en ) | 1995-06-06 | 1996-12-10 | Schuyler; John P. | Mower blade |
| US5832704A ( en ) | 1996-11-08 | 1998-11-10 | Routh; S. Jack | Mower blade assembly |
| US6978590B1 ( en ) | 2004-11-19 | 2005-12-27 | John Graham | Lawn mower blade improvement |
| US20060026941A1 ( en ) | 2004-08-03 | 2006-02-09 | Iannello Joseph P | Mower deck cleaning and lubricating device |
| US7628003B2 ( en ) | 2004-08-03 | 2009-12-08 | Iannello Joseph P | Mower deck cleaning and lubricating device |
| US20120174551A1 ( en ) | 2011-01-11 | 2012-07-12 | Hayward Randolph J | Lawn mower cleaning and mulching device and method |
| CN103548469A ( en ) | 2013-11-01 | 2014-02-05 | 苏州安必瑟斯机电技术有限公司 | Mowing machine |
| GB2552331A ( en ) | 2016-07-18 | 2018-01-24 | F Robotics Acquisitions Ltd | Improvements relating to robotic lawnmowers |
| FR3071700A1 ( en ) | 2017-10-04 | 2019-04-05 | Regis Jochaud Du Plessix | SYSTEM OF SELF-CLEANING OF THE CUTTING GRASS INTERIORING ON ROBOT MOWER BETWEEN BLADES AND CARTER |
| USD911395S1 ( en ) | 2019-03-06 | 2021-02-23 | Lambros Dimitracopoulos | Cutting blade |
| US11596099B2 ( en ) | 2013-04-17 | 2023-03-07 | Rowse Hydraulic Rakes Co., Inc. | Hay rake tooth assembly |
Patent Citations (11)
| US1414305A ( en ) | 1920-12-03 | 1922-04-25 | Sandblom Gideon Efraim | Rotatory brush or scraper for removing rust, paint, or the like |
| US2565047A ( en ) | 1946-08-12 | 1951-08-21 | Fuller Brush Co | Brush with flat wire elements |
| US2863162A ( en ) | 1956-05-16 | 1958-12-09 | William H Draughon | Snow sweeping attachment for lawn mower |
| US2957295A ( en ) | 1958-05-01 | 1960-10-25 | Briggs Stratton Corp | Grass clipping discharge for power lawn mower |
| US3051972A ( en ) | 1960-01-11 | 1962-09-04 | Vernon J Lacy | Snow removal device |
| US3184903A ( en ) | 1963-09-25 | 1965-05-25 | Leonard R Fjelstad | Attachment for rotary lawn mower |
| US3358431A ( en ) | 1965-02-25 | 1967-12-19 | Black Decker Mfg Co | Blade for lawn edger |
| US3396518A ( en ) | 1965-04-21 | 1968-08-13 | Earl B. Johnson | Rotary power lawn mower |
| US3531927A ( en ) | 1968-08-09 | 1970-10-06 | George C Wood | Rotary raking wheel tooth and mounting |
| US3753341A ( en ) | 1972-09-22 | 1973-08-21 | A Berg | Rake attachment for rotary power mowers |
| US3857226A ( en ) | 1973-10-11 | 1974-12-31 | C Sifakas | Thatcher |
Cited By (15)
| US5491962A ( en ) | 1993-11-17 | 1996-02-20 | Trim-A-Lawn Corporation | Cutting head assembly |
| US5581987A ( en ) | 1995-06-06 | 1996-12-10 | Schuyler; John P. | Mower blade |
| US5832704A ( en ) | 1996-11-08 | 1998-11-10 | Routh; S. Jack | Mower blade assembly |
| US20060026941A1 ( en ) | 2004-08-03 | 2006-02-09 | Iannello Joseph P | Mower deck cleaning and lubricating device |
| US7628003B2 ( en ) | 2004-08-03 | 2009-12-08 | Iannello Joseph P | Mower deck cleaning and lubricating device |
| US6978590B1 ( en ) | 2004-11-19 | 2005-12-27 | John Graham | Lawn mower blade improvement |
| US20120174551A1 ( en ) | 2011-01-11 | 2012-07-12 | Hayward Randolph J | Lawn mower cleaning and mulching device and method |
| US11596099B2 ( en ) | 2013-04-17 | 2023-03-07 | Rowse Hydraulic Rakes Co., Inc. | Hay rake tooth assembly |
| CN103548469A ( en ) | 2013-11-01 | 2014-02-05 | 苏州安必瑟斯机电技术有限公司 | Mowing machine |
| GB2552331A ( en ) | 2016-07-18 | 2018-01-24 | F Robotics Acquisitions Ltd | Improvements relating to robotic lawnmowers |
| GB2552331B ( en ) | 2016-07-18 | 2020-02-05 | F Robotics Acquisitions Ltd | Improvements relating to robotic lawnmowers |
| US11172606B2 ( en ) | 2016-07-18 | 2021-11-16 | Mtd Products Inc | Robotic lawnmower with passive cleaning assembly |
| US11589504B2 ( en ) | 2016-07-18 | 2023-02-28 | Mtd Products Inc | Robotic lawnmower with passive cleaning assembly |
| FR3071700A1 ( en ) | 2017-10-04 | 2019-04-05 | Regis Jochaud Du Plessix | SYSTEM OF SELF-CLEANING OF THE CUTTING GRASS INTERIORING ON ROBOT MOWER BETWEEN BLADES AND CARTER |
| USD911395S1 ( en ) | 2019-03-06 | 2021-02-23 | Lambros Dimitracopoulos | Cutting blade |
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Lawn Mower Blade Bolt Stuck – Mechanics secret tips
I know the feeling, FRUSTRATION. but we’ll get it figured out. The blade bolt can be stuck for a few different reasons. Usually, it’s a combination of rust and over-tightening.
How to remove a damaged lawnmower blade bolt
The easiest way to remove a stuck blade bolt is with an impact tool; they make the whole job look easy. Other options include:
You may not have an impact, so I’ll show you a few different options. Some of these options may not suit you; it’ll depend on what tools you have available. Best to don a pair of work gloves. Stuck bolts usually mean slipping tools.
Removing A Rounded Bolt
Over-tightening is common. Mower blades are designed to be tightened to a specific torque, which isn’t as tight as you might expect. That’s because they’re designed to slip if they hit a solid object. The slipping protects the engine from serious damage associated with a curbstone strike.
Also common is turning the bolt the wrong way; hey, it could happen to a bishop. All single-blade walk-behind mowers will have what’s known as a right-hand thread. That means, to loosen the bolt, you turn it to the left. (counter-clockwise)
I cover all you need to know pretty well in this post, but if you need more help, check out the following videos:
Blade Bolt Torque
Mower blade bolts should be torqued to spec. These bolts are usually over-tightened, and when you add corrosion, removing them can be a headache.
Only some large twin blades walk-behind mowers and some lawn tractor mowers are likely to have one only left-hand threaded blade bolt; the other bolt will be a regular right-hand thread.
How do you know which is which?
Simple, if the blade is designed to cut turning right (viewed from above), then it will be a right-hand thread; this is the most common type. To loosen a right-hand thread, you turn it to the left.
The same idea applies to twin-blade tractor mowers. However, a left-hand thread is common on some lawn tractor mowers.
So, if the blade cuts grass turning to the right, as before, it’s likely a regular right-hand thread (left to loosen). But it’s not uncommon for a tractor mower to have one of the blades turn to the left when cutting, and that usually means it’s a left-hand thread (check your owner manual) to loosen a left-hand thread, turn it to the right.
L/H – R/H Thread
A r/h thread loosens to the left. This is the most common type of thread. (counterclockwise)
A l/h threaded bolt loosens to the right. (clockwise)
Typical torque specs for blade bolts are anywhere from 35 ft. lbs. to 90 ft. lbs., you’ll need to check the spec of your mower, it’s important to get it right.
Most of the time blade bolts just get buttoned uptight and aren’t torqued to spec, and that’s OK, but you run the risk of bending the crankshaft if you hit a solid object. I advise using a torque wrench, it’s a lot cheaper than a new mower engine.
Torque wrenches are easy to use, they come in inch-pounds for smaller torque specs, but for mowers, you’ll need foot-pounds. A torque wrench from 30 to 100 foot-pounds is about right.
If you don’t have or can’t borrow one, check out this post on my 1/2 drive Teng Torque, it won’t break the bank, it covers 30 to 150 ft. lbs., it’s simple to use, calibrated from the factory, and has a flexible working range.
I get my torque wrenches calibrated every year but it gets a lot of use. If you set your torque wrench to zero after you use it and don’t throw it around, it should stay calibrated for years.
Damage – The bolt on the right has a rounded head, this kind of damage happens when a tool slips on a bolt head, or corrosion deforms it. Getting the bolt out presents a challenge.
A rounded bolt head is a real pain in jacksie. It usually happens when the bolt is old and corrosion has deformed it. Worn or damaged tools will give you the same result.
It can also happen if the wrong size tool is used. An American mower may use imperial size nuts and bolts, I know the more modern kit is metric and some mowers are a mix of both. If your mower is European or Asian it will be metric sizes.
The trouble is you can get an imperial wrench to almost fit a metric bolt, but it’s loose and will slip, which rounds the bolt head. Typical bolt sizes for mower blade bolts are Imperial 1/2″, 5/8″, 3/4″ and Metric sizes 13mm, 14mm, 15mm, 16mm, and 17mm.
Imperial or Metric, be sure your tools are a good fit.
Tools You’ll Need
Impact power tools are designed for this exact job. They cause a hammering action which helps reduce the bolt thread friction and breaks any corrosion loose. So if you have an air or battery impact tool, you going to feel like a superhero when that bolt just walks out.
Basic tools needed assuming you don’t have an impact tool: wire brush, wd40, ratchet sockets, selection of wrenches.
Other tools you’ll need if things don’t go exactly to plan: breaker bar, hammer chisel, butane torch, and if everything goes to crap, a Mig welder. In my workshop, I use an air impact tool, if you haven’t got one or can’t borrow I have other solutions for you.
But the tool I am least likely to be without is an impact tool, it just makes life really easy and saves so much time. The coolest thing about the latest generation impact tools is their mobility, cordless now packs the power of an air tool. Great for around the home and for flat wheel emergency, use it to run the jack-up and take the nuts off.
Although I still use air in the workshop, I bought a 20v Ingersoll Rand cordless for mobile repairs, I know they ain’t cheap but you won’t ever need to buy another.
If you do buy an impact tool, you’ll need to buy impact sockets too. Sure you can use regular sockets, but you run the risk of them shattering. Anyway, you’ll find all these tools on the “Small engine repair tools page”.
Tool Up – Most stuck bolts won’t need all these tools, but some do.
Removing The Bolt
Removing a stuck bolt involves trying different solutions until you ring the bell. In the first attempts, we’ll try the simple stuff and if that doesn’t move it, I have lots more ideas.
Before we start any work on our mower we need to make it safe. Pull the plug wire off and set it away from the plug. Turn your gas off if you have a gas tap, if you don’t know where your gas tap is check out “Gas tap location”.
WD40 is my favorite tool, it solves lots of problems, I also like a product called nut buster, it’s formulated for dissolving rust. Try spraying the bolt liberally above and below the blade, and allow it time to work into the threads.
Disable Mower – For safety, let’s remove the plug wire and turn off the gas.
Turn the mower over with the carburetor side facing up, stops gas leaking on the floor. (see tilting mower over)
Wire Brush to remove any rust. Wd40 Spray front and rear of the bolt and give it some time to soak in.
Impact Tool – By far the preferred way to remove a bolt. An Impact gun hammers the bolt as well as twists it, this loosens the corrosion between the threads.
An impact tool will remove the bolt in seconds and you won’t need to lock the blade. But if the bolt head is rounded, the impact tool is of no use. You’ll need a different solution.
Check out the Amazon link, some of these impact wrench surprised me.
Lock Blade – If you are not using an impact tool we’ll need to use a piece of timber to lock the blade against the body. Longer timber is better than shorter. Cut a length to suit.
Good Fit – Select a socket (6 points preferably) and check the fit. Turn the ratchet left to loosen. Using a breaker bar, or if you don’t have to improvise with your ratchet and some pipe.
Pushing down on the pipe will give you the extra power you need to break it loose. Just be sure the socket is a good fit, and it stays on the bolt head when you’re applying force.
Wrench Leverage – Turn the Wrench left to loosen. If you don’t have a ratchet and breaker bar, try 2 interlocked wrench’s for extra leverage, or use a hammer to shock the bolt.
If it still won’t budge, try tightening it slightly, this often helps, odd I know!
Striking – Try striking two hammers sharply (wear eye protection) while one is placed against the bolt head, this can help break loose any corrosion on the threads. If the head of the bolt is rounded, move on to the next solution.
Rounded Bolt – If your bolt head is rounded, try a vice grip. Get it as tight as you can, and try hitting it to the left sharply with a hammer.
Not all vice grips are the same, for this application you’ll need a flat jawed set. Check out this post on Vice-grips tools.
Chisel – This method is pretty effective, but you’ll need a new bolt, sharp metal working chisel, and a heavy hammer. With the chisel and hammer, take a sideways and downward aim at the bolt, we’re attempting to loosen it by turning it left. This will require good aim, so now’s a good time for those gloves.
Heat – Ordinarily I’ll tell you to get some heat on the bolt, the reason I haven’t introduced it earlier is that it comes with the risk of damaging the crankshaft nylon seal, which would cause the engine to leak oil.
The risk of this is fairly small, once you direct the flame and only use a small amount. We’re not going to redden the bolt, just going to heat it up.
Maybe 2 minutes with a butane torch directed at the bolt. You can now try heat with any combination of the above methods. Heat is very successful at helping move stuck bolts.
Welding – This method will obviously require a welder, when I get a really stubborn bolt with a rounded head, I take a new bolt and weld it to it. This gives me a not-so-pretty but clean bolt head to work with.
This solution has never failed me yet. You’ll need to replace the bolt. Blade bolts have a fine thread, they are a specialized bolt, getting one in the hardware store isn’t advisable.
Torque – Finally, you’ll have to move your timber to lock the blade in the other direction and torque your new bolt to spec.
Check out this post to see why it’s important to torque your blade bolt.
Related Questions
The spindle turns when removing the blades? The easiest way to prevent the blade from turning while loosening the blade bolt is to use a large block of wood to lock the blade against the mowing deck.
Lawnmower blade bolt direction? Turn the mower on its side, carburetor side up, turn the blade bolt to the left (anticlockwise) to loosen.
Hey, I’m John, and I’m a Red Seal Qualified Service Technician with over twenty-five years experience.
I’ve worked on all types of mechanical equipment, from cars to grass machinery, and this site is where I share fluff-free hacks, tips, and insider know-how.
And the best part. it’s free!
Lawn Mower
The lawn mower is a mechanical device that literally shaves the surface of the grass by using a rapidly rotating blade or blades.
For centuries, grass was cut by workers who walked through pastures or fields wielding small, sharp scythes. In addition to being tiring and slow, manual cutting was ineffective—the scythes worked well only when the grass was wet. The first mechanical grass-cutting device appeared in 1830, when an English textile worker named Edwin Budding developed a mower allegedly based on a textile machine used to shear the nap off of cloth. Budding’s cylindrical mower was attached to a rear roller that propelled it with a chain drive, and it shaved grass with a curved cutting edge attached to the cylinder. He created two sizes, large and small. The large mower had to be drawn by horses, whose hooves were temporarily shod with rubber boots to prevent them from damaging the turf; the head gardener at the London Zoo was among the first to purchase this model. Budding marketed the smaller mower to country gentlemen, who would, he claimed, find in [his] machine an amusing, useful and healthful exercise.
Mechanized grass cutting was evidently slow to catch on, perhaps because Budding’s mower was quite heavy in addition to being inefficiently geared. Only two lawn mower manufacturers exhibited their machines at England’s Great Exhibition in 1851. However, several decades later the new machines experienced a surge in popularity due to the interest in lawn tennis that arose in England during the late Victorian period. Before the turn of the century, Budding’s initial designs were improved. Weighing considerably less than their predecessors and based on the side wheel design still used in today’s most popular mowers, these refined machines were soon visible in yards throughout England.
The earliest gas-driven lawn mowers were designed in 1897 by the Benz Company of Germany and the Coldwell Lawn Mower Company of New York. Two years later an English company developed its own model; however, none of these companies mass produced their designs. In 1902 the first commercially produced power mower, designed by James Edward Ransome, was manufactured and sold. Although Ransome’s mower featured a passenger seat, most early mowers did not, and even today the most popular models are pushed from behind.
Power mowers are presently available in four basic designs: the rotary mower, the power reel mower, the riding mower, and the tractor. Because the rotary mower is by far the most common, it is the FOCUS of this entry. Pushed from behind, rotary mowers feature a single rotating blade enclosed in a case and supported by wheels. As the engine turns, it spins the blade. The blade whirls at 3,000 revolutions per minute, virtually 19,000 feet (5,800 meters) per minute at the tip of the blade where the cutting actually occurs. The best rotaries feature a horn of plenty (cornucopia) or wind tunnel shape curving around the front of the housing and ending at the discharge chute through which the mown grass flies out. Self-propelled models are driven by a chain or belt connected to the engine’s drive shaft. A gearbox usually turns a horizontal axle which in turn rotates the wheels. Some models have a big chain- or belt-driven movable unit that rises up off and settles down on the wheels.
The power reel mower features several blades attached at both ends to drums that are attached to wheels. The coupled engine drive shaft that spins the reel can also be rigged to propel the mower, if desired. Overlapping the grass, this machine’s five to seven blades pull it against a cutting bar at the bottom of the mower. Then one or more rollers smooth and compact the clippings as the mower goes over them. Reel mowers are more efficient than rotary mowers because the latter actually use only the end of the blade to do most of the cutting, whereas the fixed blades in a reel mower cut with the entire length of both edges. However, rotary mowers are easier to manufacture because the basic design is simpler, and they are also favored over reel mowers on most types of turf. By industry estimates, most of the 40 million mowers in use on any given summer Saturday are rotary mowers.
Raw Materials
The typical gas-powered walk-behind mower may have as many as 270 individual parts, including a technologically advanced two- or four-cycle engine, a variety of machined and formed parts, various subassemblies purchased from outside contractors, and many pieces of standard hardware. Most of these pieces are metal, including the major components: mower pan, handlebar, engine, and blades. A few, however, are made of plastic, such as side discharge chutes, covers, and plugs.
The Manufacturing Process
Manufacturing the conventional rotary lawn mower requires precision inventory control, strategic placement of parts and personnel, and synchronization of people and tasks. In some instances, robotic cells are used in conjunction with a trained labor force.
Unloading and distributing the components
- 1 Trucked into the plant’s loading dock, the components are moved by forklifts or overhead trolleys to other centers for forming, machining, painting, or, if they require no additional work upon arrival, assembly.
After arrival at the factory, the various parts are formed, painted, and assembled. The mower pan is machine-stamped before undergoing plasma cutting, which creates apertures in the pan. Other parts are welded to the pan, and then the entire shell is prepared for an electrostatic paint coating.
The mower pan
- 2 The steel mower pan, the largest single part and one used in various models, is first machine-stamped under great heat and pressure. The pan is then transported to a robotic cell, where a plasma cutter creates apertures in it. The term plasma refers to any of a number of gases (argon is commonly used) that can be raised to high temperature and highly ionized by being passed through a constricted electrical arc. When directed through the narrow opening of a torch, this hot, ionized gas can be used for both cutting and welding.
- 3 After other elements such as baffles (deflecting plates) are welded on, the finished pan and a number of other exposed parts are powder painted in a sealed room. Powder painting entails thoroughly washing the parts in alkaline and phosphate solutions and rinsing them to seal the surfaces. The parts are then attached to overhead conveyors and run through a paint booth. Fine paint particles are sprayed from a gun that imbues them with an electrostatic charge—opposite to the charge given to the part being painted—that causes the paint to adhere to the surface of the parts evenly. Next, the parts are baked in ovens to produce a permanently fixed, enamel-like coating. The pan
The shell is painted electrostatically and then baked to seal the paint. Meanwhile, the handelbar is bent and pierced by robots, and then the remaining components are assembled.
Shaping the handlebar
- 4 The handlebar is created in a robotic cell whose mechanical arms perform three operations. In a bender, the tubing is first bent in at least four places. A second press operation flattens the ends, and a third pierces fourteen or so round and square holes in the tubing. These holes will accommodate the starting mechanism, blade and wheel drive control, and the pan attachment. The finished handlebar is then transported to a subassembly station, where many of the controls are added.
Other subassemblies
- 5 The other major subassemblies are also created at various plant centers using formed, machined, or purchased materials and standard hardware. Parts purchased from outside suppliers include engines built to manufacturer’s physical and performance specifications, tires, shift mechanisms, wiring harnesses, and bearings. Injection-molded plastic parts are purchased for use in side discharge chutes, covers, and plugs. Injection molding refers to a process in which molten plastic is squirted into a mold and then allowed to cool. As it cools, the plastic assumes the shape of the mold.
- 6 Assembly teams put the six or more major subassemblies together on a rolling line at a pace determined by the task and skills required. The engine is first placed upside down in a frame fixture, and the mower pan is bolted down along with the drive mechanism. Then come the rear axle, brackets, and rods to secure the shift controls. The blade and accompanying clutch wheels and parts are fastened to the engine through the pan opening with preset air-driven torque wrenches. After another team member adds hardware and wheels, the unit is flipped onto its wheels. The handlebar is attached, and control cables are secured and set. Finally, the mower—each mower—is performance-tested before shipment to dealers, where some final set-up adjustments are made.
Quality Control
Inspectors monitor the manufacturing process throughout the production run, checking fits, seams, tolerances, and finishes. In particular, the paint operation is scrutinized. Samples of each painted part are regularly pulled off the line for ultrasonic testing, a process that utilizes the corrosion activity created in a salt bath to simulate 450 hours of continuous exposure to the natural environment. Painted parts are also scribed and the deterioration of the exposed surface watched for tell-tale signs of rust. If needed, the paint or cleaning cycles are adjusted to assure high quality and durable finishes.
Final performance testing—the last step in the assembly sequence—guarantees reliability and safety for users. A small quantity of a gas/oil mixture is added to each engine. A technician cranks the engine and checks its rpm with a gauge; drive elements and safety switches are also checked. As required by current Consumer Product Safety Commission regulations, the mower blade, when running, must stop within three seconds after the control handle is released.
The Future
Like many other machines, the lawn mower will benefit from the development of new and more efficient power sources. A recent invention is the solar-powered lawn mower, which uses energy from the sun rather than gasoline as fuel. It needs no tuneups or oil changes, and it operates very quietly. Perhaps its biggest drawback is the amount of energy its battery can store: only enough for two hours of cutting, which must be followed by three days of charging. However, as batteries with more storage capabilities are developed, this drawback will disappear.
Where To Learn
Books
Davidson, Homer L. Care and Repair of Lawn and Garden Tools. TAB Books, 1992.
Hall, Walter. Parp’s Guide to Garden and Power Tools. Rodale Press, 1983.
Nunn, Richard. Lawn Mowers and Garden Equipment. Creative Homeowner Press, 1984.
Peterson, F. Handbook of Lawn Mower Repair. Putnam, 1984.
Periodicals
Buderi, Robert. Now, You Can Mow the Lawn from Your Hammock. Business Week. May 14,1990, p. 64.
Robo-Mower. The Futurist. January-February, 1989, p. 39.
Kimber, Robert. Pushing toward Safety: The Evolution of Lawn-Mower Design. Horticulture. May, 1990, p. 70.
Murray, Charles J. Riding Mower’s Design Reduces Turning Radius. Design News. April 5, 1993, p. 81.
Smith, Emily T. A Lawn Mower That Gets Its Power from the Sun. Business Week. February 11, 1991, p. 80.
The Best Zero-Turn Mowers of 2023
These achieve the rare feat of making lawn mowing fun.
By Roy Berendsohn Published: Mar 1, 2023
When it comes to yard work, zero turn mowers do the impossible. They make lawn mowing fun. They accomplish this by putting unprecedented speed, control and maneuverability at the disposal of the person mowing the lawn. The so-called “zero turn” feature of these mowers converts a grass cutting machine into something akin to an amusement park ride. You steer the machine with two levers—the left lever controls the left wheel, the right lever the right wheel. With that steering setup, you can zoom over the landscape cutting straight lines, curves, or pivot the mower into and out of a corner. What’s not to like?
Read on to understand how these agile grass cutters work, how we go about testing them, and see some candidates that we’ve recently tested as well as some that we haven’t but that we think look particularly promising.
How Zero-Turn Mowers Work
A zero-turn riding mower consists of an operator platform, a frame and wheels, an engine (or battery bank), transmissions (or motors), and a pair of control levers commonly known as lap bars. In gas mowers, the engine powers a pulley system. One group of pulleys drives the blades, another group powers a pair of transmissions–one at each rear wheel. When you move the lap bar forward or back, you are directing the transmission to go faster, slower, or even turn the opposite way. When one drive wheel turns clockwise and the other counter clockwise, the mower pivots. When the wheels rotate at different rates, the mower turns in an arc-shaped path. When the lap bars are in the neutral position, the mower stops. Aside from a parking brake, there’s no other braking mechanism. Battery-powered zero-turn mowers work the same way, but have separate motors to drive the rear wheels and one for each blade inside the mower deck.
When it comes to transmission, most mowers have a Hydrogear EZT—a well-known and cost-effective residential-grade transaxle with a reputation for durability.
Some mowers use a deck stamped from one piece of steel, others use a deck fabricated from multiple pieces and welded together. A fabricated deck can be built from thicker steel at a lower cost than it would be able to be built otherwise. Once you’re talking about stamping metal as thick as 10 gauge (about 1⁄8 inch thick), the cost of stamping such a deck would push up the mower’s price beyond what most people are willing to pay. The decks in the mowers below range from 42 to 52 inches, a typical size in this class of product. When powered by these engines and the Hydrogear, these mowers will deliver a decent cut quality at their rated top speed of 7 mph. Note, however, that cut quality declines steeply if you maintain that speed in very thick grass or on uneven terrain.
As to the electric mowers, they represent the leading edge of the technology in this category. These are remarkable and expensive mowers powered by large-voltage lithium-ion batteries. If you’re interested in reducing mowing noise and simplifying your maintenance routine by eliminating gas and oil, they’re worth a look.
Selecting a Zero-Turn Mower
Everyone would like to select the biggest possible zero-turn mower with the hope of whittling a big grass cutting job down to size as quickly as possible. Reality usually intercedes because these machines are expensive and the wide range of options available today quickly drive up the cost. Roughly speaking, you start somewhere in the range of a mower with a 42-inch deck costing in the vicinity of 3200 to 3500 and move up in increments of 1000 to 1500 until you reach entry-level commercial-grade equipment that costs 7000 to 8000.
Again, speaking in terms of approximation, a mower with a 42-inch deck will cut a two-acre lot (that takes into account that the house, driveway, outbuildings and various landscape features are taking up some of that space). Use a mower with a larger deck to cut anything over two acres. But here’s the caveat. That entry-level ZTR mower (3200, say) with a 42-inch deck will wear out faster and need more maintenance than a mower with a 50-inch deck, a heavier frame, larger engine and higher quality transmissions, and thicker deck with more robust blade spindles, costing 4500.
In the simplest possible terms, you can cut a smaller area with a larger mower and expect more longevity out of the machine (not to mention a nicer mowing experience) or you can cut a larger area with a smaller machine and encounter more maintenance and a mowing experience that will be, we might say, a bit more rugged.
But there are still other factors to consider, in selecting a mower other than deck size and your budget. Larger mowers take more space in a garage or outbuilding. And a mower with a 50-inch or even 60-inch deck, as useful as it might be in getting the job done more quickly, may not fit through a fence’s gate, and it might be more difficult to maneuver in tight spots without creating scalp marks on the lawn from a lot of close-quarter pivoting.
Carefully consider all these factors when shopping for a mower: your budget, maintenance and whether you will perform that work yourself, mowing speed and time, maneuverability and trimming in tight areas, the importance that you place on your comfort while mowing, cut quality, longevity, storage, and access to the landscape.
How We Select and Test
There’s only one way to test a mower, and that’s to cut grass with it. But we also do more than mow.
We raise and lower the deck and adjust the seat. We look at service point access (the air filter, the spark plug, and the oil filter) and how easy it is to remove the deck. We mow approximately an acre with each mower, considering cut and mulching quality while running uphill, downhill, across washboard, and along sidehills. (On sidehills, we’ll mow surfaces pitched up to approximately 20 degrees; manufacturers generally recommend not going steeper than 10 degrees, but we like to be thorough.) We evaluate power and speed relative to cut quality—we investigate whether the mower delivers a decent cut mowing at full speed. When mowing in damp conditions, we look at whether the mower’s tires accumulate grass and how effectively it discharges moist clippings. Finally, we test maneuverability (these machines are, generally, very nimble) and how readily they come to a stop when you back off the lap bar control levers.