Welcome to my site! And in this article, we will consider how to assemble the gearbox of an electric screwdriver. For some people this information is needed for cognitive purposes, for others. for practical purposes, to be able to repair this mechanism of an electric screwdriver on their own. Well, let’s satisfy the interest of both.
The gearbox of an electric screwdriver has a planetary mechanism. Where does this name come from and what does it all mean??
The thing is that in such a gearbox there are several gears. One of them is the gearbox and the others are driven. And the driven gears rotate around the rotating driving gear, and they themselves also rotate around their own axis. That is, this whole system resembles the movement of the planets around the sun, hence the name “planetary. In this case, the leading central pinion is commonly called the solar pinion.
The movement of all gears is shown in the illustration below.
As we can see the sun gear rotates in the middle. This would drive the smaller gears, called satellites. And for the satellites to rotate around the sun gear, there is an outer gear, commonly referred to as a crown gear. And the base on which the satellites sit is called a rudder. In the picture it is green.
If we translate this scheme to an electric screwdriver, the sun gear will be the one on the engine (so it rotates), and the driver will be the element that transmits the rotation to the chuck. The picture below shows it more clearly in relation to the screwdriver.
As you can see from the diagram above, the driver turns more slowly than the sun gear. That’s what the gearbox is for. to reduce the speed of the chuck compared to the speed of the motor and to increase the torque (tightening force) at the same time.
Some may say: why bother making such a gearbox, when you could simply use one small pinion as a drive and a second large pinion as a slave to decrease rotation and increase torque. This is actually the way it is done on conventional drills.
Such a scheme is not suitable for screwdrivers, because it is designed to take more loads than a drill. Yet screwing in screws requires more force than drilling. The planetary reduction gear enables the load to be distributed evenly over several gears instead of just one, like in drills. This results in a much higher torque.
Yes, I know that drills with adjustable speed are also used by many people for screwing self-tapping screws and they seem to be ok. But no matter how you spin it, with the same motor power, any electric screwdriver will still have more torque. And since the gears of its planetary gearbox receive less load, they will last longer. In addition, the motor of an electric screwdriver will also wear out more slowly than a drill, for the same loads.
However, the above blow-up diagram of the electric screwdriver gearbox does not quite correctly reflect what screwdrivers actually have. It’s just that the diagram shows only one stage, after which the driver is directly attached to the chuck. In practice, however, at least two stages are usually used. That is, the driver of the first stage has a pinion on the reverse side, which becomes the sun in the next stage, which usually already has five satellites. In this way you already have two planetary gears in one gearbox. This puts even less strain on the entire gearbox and the motor.
If we talk about two-speed screwdrivers, they have three steps. In the first speed, they’re all engaged, but in the second speed, only two of them are engaged. A special driver on the first stage and a special pinion on the second stage are used in this reducer.
The special driver is characterized by having teeth on its outer rim, thus becoming a pinion.
What makes the second-stage crown gear different is that it can be slid along the gearbox. That is, when the speed selector on the housing moves, it’s this gear inside that moves. It looks like this:
Inside the plastic frame, the pinion turns freely. However, on the back side it has projections.
These projections fit into special slots on the gearbox housing when the first speed is engaged. In this position it can no longer rotate and acts as a normal second stage planetary crown mill. By the way, the wear of these grooves is often the reason why the electric screwdriver does not spin in first speed.
When the second speed is engaged, this pinion moves backwards:
In this position it will be in mesh with the outer teeth of the first stage driver, which is fixed in the gearbox:
At the same time the crown gear continues to be in mesh with the second stage satellites, but it will be moved out of the locking notches of the gearbox housing and allowed to rotate.
So what does shifting to second speed do?? The following happens: The first stage driver turns the whole second stage with the crown mill, the satellites and the second stage driver. The second stage driver will then have the same rotation speed as the first stage driver. So, there is no downshifting and instead, the rotation of the first stage is transmitted directly to the third stage. That’s why I wrote above that only two stages are engaged in the second speed. From the description it is clear that this is the first and third.
I’m sorry if I wrote it too complicated, but it couldn’t be simpler. And so, in fact, this is all you need to know about the reducer of an electric screwdriver. And here I will finish the article. see you next time!
Design and principle of operation
The gearbox is a complex mechanical transmission unit through which the axis of the motor-power unit transmits the torque to the chuck.
There are two or three gear stages in a gearbox.
The design of the “domestic” two-mode electric screwdriver assembly includes:
- The plastic housing is a small drum that attaches to the chuck. The body itself is fixed stationary and the chuck shaft is inserted into a clamp on one of the transmission plates;
- 2 or 3 gear plates (driver). round metal plate, on one side of each plate there are 3 lugs for small gears. On the other side of one of them is a clamp under the chuck shaft, and the other (or 2 others) has another t.н. A “planetary” gear that rotates three small gears;
- 6 or 9 small gears (three of each: they may be of the same or different thickness) are the so-called “satellite” gears, which are mounted and rotate freely on the protrusions of the transmission plates. With their teeth, they interact with the sun gear between them and with the ring gear, which is placed on the inner surface of the housing;
- ring gear. a metal ring with teeth on the inside and small protrusions on one of the outer rings. On these protrusions and ball bearings it is laid on the inner surface of the housing.
Parts are lubricated, assembled in series, and installed inside an o-ring gear that lies inside the housing drum (it has a seal with recesses for the ball bearings and gear lugs). After that, the surface of the open satellites is closed by a metal washer, in the center of which there is a hole, into which the shaft of the motor with another gear attached to it enters.
During operation of the electric screwdriver, the gear wheel on the motor shaft rotates the upper satellites, and they, rotating around their axis and, by the ring gear, respectively, transfer the motion to the next driver. Depending on the number of plates and small pinions. the rotation speed will be proportionally reduced.
As can be seen from the structure of the reduction unit. they are subdivided depending on the number of transmission plates into:
Reference. On the presence of stages depends on such an indicator as the number of speed modes of the device, and this, in turn, will affect its cost.
Another indicator by which gears are subdivided is the material from which its parts are made.
Satellite gears are used in the manufacture:
- plastic. These designs are relatively lighter, but their reliability is lower than their metal counterparts;
- metal. They are durable and will operate “like clockwork” with proper care and lubrication.
Important. The disadvantages of metal parts are an extension of their advantages. they are heavier than plastic and cost more. In this case, if the electric screwdriver is used without violation of operating rules 2-3 times a year, the master is unlikely to feel any difference from what material the gear parts are made of.
Electric screwdriver repair with your own hands
To troubleshoot a device, you need to disassemble it by removing the housing and disconnecting the main elements of the tool from each other. Repair of any equipment can be divided into several stages. In the case of an electric screwdriver, this is as follows. In this case, in each individual case, the steps of repair may differ depending on the cause of the failure, which must be eliminated.
Electric screwdriver chuck threads
Structurally, this movable element is fixed in the tool body in three ways:
The Morse taper fastener has been known for many years. The shaft is shaped like a cone that follows the shape of the surface inside the chuck. the same cone. By combining them in a certain way a secure connection is obtained.
The connection between the shaft and the chuck by means of a threaded connection is the presence of a thread on the end of the shaft on which a chuck with the same thread can be freely screwed on.
A fixing screw is often used as an additional fastener. Its head has notches for a Phillips screwdriver, as well as left-hand thread. You can see this screw by unscrewing the cams that cover it.
To find out which fastener your tool has, take a good look at the housing of the tool. Each type of mounting has its own designation. For example: 1-6 V10 would mean that the chuck is fixed by means of a Morse cone of size B10 and bits with a shank diameter from 1 to 6 mm can be used to it. If there is such a record: 1.0-11 M 12 x 1.25. you will know that it should use a shank from 1 to 11 mm, the metric thread has a section of 12 x 1.5 mm. Foreign manufacturers use figures in inches, for example, 1.0-11 ½. 20 UNF.
In this article we have considered the main problems that arise during the operation of the tool, paid attention to such a critical component in the design of an electric screwdriver, as a chuck. At the same time we have analyzed how it is fixed in the design of an electric screwdriver, gave some tips on how to repair it with your own hands, and also tried to cover in general terms the ways of solving repair problems.
Chuck removal: Bosch electric screwdriver
Bosch electric screwdrivers are generally equipped with a fixing screw.
- We put a key in cams and tighten a couple of clicks.
- The tool is placed on the edge of the table.
- Press the stop pushbutton to release the chuck retainer on the shaft.
- The cartridge is removed counterclockwise.
Ремонт пеоратора Metabo UHEV 2860. 2 Quick
All actions require special attention and consistency in disassembly/assembly.
Having received theoretical knowledge about the types of chucks, it will be easier for you to repair an electric screwdriver Interskol, Hitachi, as well as other manufacturers.
Breakdowns in the mechanical part. how to eliminate
It is easier to detect a mechanical problem than an electrical one. This is due to the fact that any mechanical defects are audible. The main signs of mechanical malfunctions of the devices in question include:
Разборка пеоратора Metabo UHEV 2860-2 Quick часть 2.
- Occurrence of extraneous sounds
- Vibration and chuck beating
- You can hear the engine of the tool, but the chuck does not rotate
In order to repair the device and eliminate mechanical defects, you must first of all disassemble the housing. Knowing the construction of an electric screwdriver, it will not be difficult to fix any breakdowns in the mechanical part. If you hear noises from the machine, that is a sign that the sleeves and the armature bearings are worn, they need to be replaced. If the bearing and bushings are worn, they need to be replaced, but first these parts must be purchased. It can be difficult to buy, as it is almost impossible to find spare parts for outdated models of tools.
In addition to bearing failure, the gearbox on an electric screwdriver can break. A number of malfunctions of this device include:
- Gear shaft becomes warped from heavy loads
- The gear surfaces wear out
- Pin on which satellite pins are fastened breaks
- The bearing or hub in the gearbox is worn out
Most often it is the gearbox that fails, or to be more precise, its component parts. the gear wheels. Causes of gearbox failure include:
- Improper use of the tool
- Severe loads for which the device is not designed
- Lack of grease
- Material from which the units are made
If the electric screwdriver is “old school”, that is, its gearbox consists of steel gears (instead of plastic ones), then it is better to repair it than buy a new one. To do this, you need to disassemble the device, inspect it and find the cause of the problem. When repairing the gearbox it is required to clean the mechanism and parts from outdated grease, and apply new lubricants. If there are damaged gears, they need to be replaced. Do not rush to dispose of faulty gears as you will need to buy the exact same parts (take them as a template).
To self-repair the mechanical part of the screwdrivers do not have unnecessary questions, below is a table that shows the main signs of mechanical problems, as well as ways to fix them.
|Signs of tool failure||Ways to troubleshoot|
|Occurrence of unusual noises and humming||If when working with the tool begins to appear strange sounds, it indicates the wear of the bearings. To eliminate the breakage you need to check the integrity of the motor armature and gearbox bearing. If the bearings are intact, the bushings must also be checked for signs of wear. The bearing sleeve is usually worn out|
|Vibration||Warping of the gear shaft, which can lead to a strong vibrating and wobbling motion. To solve the problem you need to disassemble the housing, assess the breakage and make an appropriate decision on the replacement of the part|
|Chuck breakage occurs||If a run-out of the cartridge is detected, it is necessary to check the quality of its fixation. The part is fastened with a bolt that is located inside the part (to see the bolt, you must move the jaws apart). To screw in the chuck, the bolt must be turned to the left side, not to the right, because it has a reverse thread|
|Jamming||If the tool is jammed and the motor is still running but the chuck won’t turn, you need to take apart the tool body and check the gearbox. Tool jamming indicates a dislocation of the satellites, a disruption in the integrity of the gears, or a breach in bearing integrity. To fix the failure, you need to disassemble the electric screwdriver and find the cause of the jamming|
|Cracks and spinning at the switch position||Gearbox faulty. To fix it, you need to disassemble the tool, and inspect the integrity of the mechanism|
Frequent Screwdriver Malfunctions
In order not to forget how to assemble the disassembled electric screwdriver, all parts must be stacked in the order in which they were removed. Almost all wrenches are of the same design, so the faults are identical. It can be a worn bushings, brushes or a broken bearing.
Tool does not turn on
No matter what brand of electric screwdriver you have Bort (Bort), Hilti, Pit, Sparky, Sturm (Sturm), Soyuz, Vihr, Diold, Yermak, Zubr, Elti, Koln, Vortex or Patriot. First you must verify that the battery is serviceable and the battery charge is present.
If the tool doesn’t turn on, it could be:
- No power (for electric screwdrivers).
- No charge in battery (for wireless models).
- The trigger is defective.
- The contacts in the battery plug or where the brushes are fastened are in a bad condition.
An electric screwdriver has a motor enclosed in a special case. There is also an armature and brushes. To check the condition of the motor, you need to disconnect the wires going to the start button. The resistance of the armature winding must be measured with a multimeter. If the value is low, the instrument will show a short circuit. If there is no value, it means there is a fault somewhere in the live wire. If the armature is defective, the electric screwdriver loses power and sparks occur during operation. This may be accompanied by smoke and complete shutdown of the machine.
To replace the brushes, you need to disassemble the electric motor. Here you need to bend the clips on the end part of the motor and knocking lightly with a hammer on the shaft, knock it off the rotor. Then remove the cover and remove the defective brushes. These elements are considered consumables, so they are replaced with new ones.
Repair of the electric screwdriver gearbox
Sometimes the electric screwdriver makes strange noises during operation. The gear teeth in the gearbox have worn out. In this case, you can grind a small bolt to size and install it in the worn area. The bolt should be countersunk before mounting.
Breakdowns in the electrical part. how to identify and repair
an electric screwdriver is a versatile tool and is not only suitable for working with fasteners. If the speed is adjustable, it can be used for drilling. No one is surprised that an electric screwdriver can stir mortar or drill a hole in winter fishing.
It is not uncommon for the electrical part of the unit to malfunction:
It makes no difference which electric screwdriver has the problem. If the tool does not start, check the battery for charging. To do this, the battery is charged for 1-2 hours and put back on the electric screwdriver. If the unit does not turn on again, using a multimeter, you need to make a diagnosis.
Many users wonder how to disassemble the battery of an electric screwdriver. Here you need to disassemble the battery case. to remove the cassettes of several cells. These so-called “banks” supply the tool with the right voltage. You can’t disassemble a battery without a certain amount of skill. It is better to entrust this matter to people who are well versed in this matter.
Problems with the button
The pins on the push button are most often burned out. To deburr them, you will need a fine grit sandpaper. This applies to the collapsible button. If the button is not disassembled, it must be replaced with a new one. You can check the operation of the button with a multimeter. To do this, disconnect the battery and connect a gauge to the output terminals. In case of faulty starting the multimeter will show zero value.
The quick-clamping fastener
The quick-change clamp is clogged with dust, metal chips and sand during operation. The cartridge begins to jam, extraneous noise and crackling appears. For troubleshooting remove the lower coupling. Use a thin screwdriver to pry it clockwise. Then remove the metal ring with a hammer and long screw. After disassembly all elements of the chuck must be cleaned and lubricated. Reassemble in the reverse order.
Before repairing, study the design of the electric screwdriver
Frequent screwdriver malfunctions
In order not to forget how to reassemble a disassembled electric screwdriver, all parts must be stacked in the order in which they were removed. Almost all wrenches have the same design, and therefore the faults are identical. It could be bushings, brushes, or bearings that have come apart.
Tool will not turn on
No matter what brand of electric screwdriver is available Bort (Bort), Hilti, Pit, Sparky, Sturm (Sturm), Soyuz, Vihr, Dyold, Yermak, Zubr, Elti, Koln, Vortex or Patriot. First it is necessary to check that the battery is in good condition and that there is some charge in the cell.
If the tool does not turn on, it may be:
- No current in the mains (for electric screwdrivers).
- No battery charge (for cordless models).
- The trigger is out of order.
- Bad contacts in the battery socket or brush brackets.
The electric screwdriver has a motor that is enclosed in a special case. The armature and brushes are located in the same place. To check the condition of the engine, you need to disconnect the wires to the start button. The resistance of the winding on the armature is measured with a multimeter. If the value is low, the instrument will show a short circuit. If there is no value, then there is a fault somewhere in the live wire. If the armature is out of order, then the power of the electric screwdriver is lost and sparks appear during operation. This can be accompanied by smoke and complete shutdown of the machine.
To replace the brushes, you must disassemble the electric motor. Here you need to bend the clips on the end of the motor and lightly tap with a hammer on the shaft, knock the rotor from it. Then remove the cover and take out the defective brushes. These elements are considered to be consumables, so they must be replaced with new ones.
Electric Screwdriver Gear Repair
Sometimes the electric screwdriver makes strange noises during operation. The teeth on the gear wheel in the gearbox are worn out. In this case, you can grind a small bolt to size and insert it into the worn place. The bolt must be tapped before it is installed.
Electrical breakdowns. how to identify and fix them
The electric screwdriver is a versatile tool and is not only suitable for working with fasteners. If it has speed control, it can be used for drilling. No one is surprised that you can use an electric screwdriver to stir mortar or drill a hole in winter fishing.
It’s not uncommon for faults to occur in the electrical part of the unit:
It makes no difference in what electric screwdriver malfunction. If the tool does not start, you need to check the battery for charging. To do this, the battery is charged for 1-2 hours and put back on the electric screwdriver. If the unit does not turn on again, then using a multimeter you need to make a diagnosis.
Many users wonder how to disassemble the battery of an electric screwdriver. Here you need to disassemble the battery housing. to remove the cassettes from several elements. These “banks” supply the right voltage for the tool. You won’t be able to disassemble the battery without some skill. It is better to entrust the matter to the people who know this question very well.
Problems with the button
Most often the contacts of an ON/OFF button get burnt. To grind them you need a fine-grained sandpaper. This applies to the collapsible button. If the button is indestructible, it must be replaced with a new one. You can check if the button is working properly with a multimeter. To do this, disconnect the battery and connect the gauge to the output terminals. In case of faulty start-up the multimeter will show zero value.
The quick-change clamp gets clogged with dust, metal chips and sand in the course of operation. The cartridge begins to jam, extraneous noise and rattle appears. For troubleshooting, the bottom coupling must be removed. Use a thin screwdriver to pry it clockwise. Then you need to remove the metal ring with a hammer and a long screw. After disassembly all elements of the cartridge should be cleaned and lubricated. The reassembly is made in the reverse order.
Before repairing, you need to study the design of an electric screwdriver
Finding the Fault and Repairing the Electric Screwdriver Gearbox
People were able to successfully fix various elements with the help of nails long time ago, but it was not so long ago that people started to use nails with spiral groove. The spiral of the screw helps it to cut into the material better, and the notch on the head makes it possible to connect the tool and the screw to create more pressure when screwing it in.
Self-tapping screws are different because of the different types of head profiles, but the most popular are instances with special notches for the cross and spline.
It is clear that it is almost impossible to screw these self-tapping screws in without a screwdriver. With it, the process will be easier, except for the fact that the self-tapping screws themselves may be more than a hundred.
To simplify the whole screwing procedure was invented drill with a gearbox for manual use. A part of the screwdriver was fixed in the chuck, and all that was left to do was to twist the handle to make the chuck rotate. The disadvantage of such a method was in periodic tearing off the notch screwdriver, and the speed was extremely difficult to control, which led to constant tearing off the edges of screws. In Soviet times, because of these situations, all the self-tapping screws were hammered into the material.
A few decades later finally a screwdriver was invented, and everything happened much easier, because the edges were not torn off, and installation became possible even without having power outlets, because the device electric screwdriver implied the presence of the battery. The electric screwdriver itself is designed for tightening and unscrewing screws, nuts and self-tapping screws, but some models can drill and chisel. This thing is very convenient in everyday life, but at times it breaks down, and then an urgent quality repair is required.
Some models of screwdrivers are equipped with a device for automatic feeding of screws
Types and causes
As a rule, the gearbox always fails in an electric screwdriver. Why it happens? Of course, because of the high level of stress it is subjected to. The most common form of failure is warping of the main shaft and chuck. This fault causes the entire tool to vibrate.
Another breakdown is the wear of the bearing of the shaft with a chuck or bearing sleeve. If the deformation received only the bushing and bearing, and the shaft remained uninjured, the repair work can be very quickly made by yourself, since it is sufficient to simply replace the worn part, but if during the inclusion of an electric screwdriver its motor first starts to function for a couple of seconds, and then abruptly stops, then the gearbox is broken. In such cases it is easy to see that the pin with which the satellite satellite bearing previously transmitted speed to the main shaft has been broken. In this situation, you can sort everything out by installing an updated driver, but if it is also damaged, you will have to change the entire reducer.
When the gear teeth are damaged, the gearbox also ceases to function properly, since long operation with worn gears causes many parts that are part of the tool’s composition to deteriorate.
How the two-stage gearbox of an electric screwdriver works
The principle of the entire system is as follows:
- The sun gear of the motor allows the satellites to rotate. The rotation itself is made by the trajectory in the form of a circle of the ring gear. Therefore, it is clear that the driver rotates at a slower pace than the motor itself.
- Then the first drive transmits the torque to the second three satellites. The transmission process is carried out through the sun gear. The second triplet also turns in a circular motion, so that the second carriage takes on far fewer revolutions. It integrates with the main shaft of the chuck.
The whole system has a mechanism for the critical level of load which also has a finite number of holes. They are made to allow the spring loaded fingers with the ends hardened by means of a high frequency current to be subsequently inserted into them. Such a system has a hardened sleeve edge which belongs to the gearbox.
The sleeve is also fitted with notches that have been created for the fingers of the first disc. The finger pattern can be adjusted during the simple screwing or unscrewing of the wrench, which is due to the fact that this mechanism has permanently reinforced or compressed springs. Excessive pressure is caused by dragging the ratchet fingers, so that the work of turning the chuck in the gearbox ends.
This is how a two-stage gearbox is structured.
All the gearboxes of different screwdrivers are arranged according to the same principle, but they differ only in the number of satellites, for example, a three-stage gearbox has simply acquired an additional mechanism.
It is also worth noting that the electric screwdriver gearbox device includes unusual gears of cylindrical, conical and worm type. To prevent them from falling out, they are inserted at a certain angle when the tool is assembled and this prevents them from falling out when the entire device is tilted.
Gear ratio never changes. Adjusting the number of chuck rotations and the frequency of blows is carried out with a special electronic regulator. There are also tool models that have gearboxes with two speeds. The gearbox can be removed from the ratchet body. The chuck is fixed by means of a screw, which in turn can be unscrewed thanks to the right-hand thread provided in the chuck.
During the rotation of the chuck under load, there is always a need for more force, for example, when the final stage of screwdriving comes. Then the load level control starts working. The force of the regulator springs is not enough to hold the ring gear and it comes off the balls. It turns out that a clicking sound is heard when the cartridge stops rotating.
The whole process of working with the device should not last more than 15 minutes, because each quarter of an hour should be accompanied by cooling of the device, because the uninterrupted operation of the device reduces the operating period of the device.
What are the gearboxes
There are different gearboxes for screwdrivers according to the number of stages: there are either two or three.