The design of grinders does not cause problems in case of repair or maintenance work, related to their assembly / disassembly. This is one of the benefits of operating this power tool. However, when disassembling, for example, a gearbox, work is required with a high degree of accuracy. This is due to the materials used (aluminum, magnesium alloys, plastic), not very strong. The use of “hard” methods of working with threaded joints may violate their integrity, which will create additional problems. Some effective methods for repairing reducers of grinders are given in this article.
An angle grinder converts electrical energy into the mechanical action of the tool on the subject of processing. Therefore, its design consists of from electrical and mechanical parts. The bevel gear just represents the main element of the mechanical part of the angle grinder. It consists of the following units and parts:
- gear housing;
- spindle on which the working tool is located;
- driving bevel gear located on the rotor of the electric motor;
- driven bevel gear located on the spindle;
- rolling and plain bearings serving as bearings for transmitting rotation.
Most common malfunctions
Gear set for INTERSKOL UShM-2300Wt; DWT-230 (74х15х49 tooth., 21х10х12 tooth.) ACECA. Photo 220V
The main reasons for the failure of the grinders due to gear failure are as follows.
- In the process of continuous operation gear wear. In this case, a "rustling" noise appears, it is possible for the bevel gears to slip relative to each other. Poor lubricant or its lack accelerates the wear of the conical pair.
- Bearings also have a limited resource. application. If they are not replaced in a timely manner, a complete destruction of the integrity of the design of the bearing assembly can occur. The reason for checking it is increased noise and vibration during operation of the angle grinder, strong heating of the gear case.
- Occurs development of bearing seats. Here you can radically solve the problem by replacing the gear housing.
- Not excluded the possibility of breakage of the fixing elements gear construction: nuts, screws, dowels, retaining rings and other similar parts.
Necessary tools for disassembling the angle grinder
Greasing for a reducer UShM Makita, 30 grams. Photo AllInstruments.ru
Dismantling the gearbox angle grinder should be done at a trained workplace, where there are no unnecessary details. This is necessary so as not to lose the small structural elements of the gearbox. Workplace need equip with the following tool and equipment:
- bench vise;
- set of wrenches and screwdrivers;
- various types of hammers. from wooden to steel;
- tool for working with circlips;
- gas key;
- pullers for bearings and gears pressed onto the shaft;
- for high-quality assembly of bearing assemblies, it is good to have the appropriate press equipment;
- in its absence, you can use extensions of various designs;
- rags with detergents (kerosene and other similar liquids);
- the presence of lubricants.
We disassemble the angle grinder correctly, video
There are many companies specializing in the production of angle grinders. The basic principles of the design of grinders for all firms are almost the same. However, there are some features that should be considered when repairing grinders of a certain brand. The experience of such a repair is presented by the masters in video formats, it is presented below.
An overview of one of the household models from Bosch angle grinder is presented in the next video. It disassembles the gearbox, after which visual bevel gear inspection. The presence and condition of the lubricant is determined. It is possible to determine the degree of gear wear. In this case, since the angle grinder is new, you can only make sure that the spindle is on single bearing in the form of a bearing slip and bevel gear. she spur. The author attributes these design features of this model to the Bosch angle grinder to disadvantages. Indeed, the resource of work is such an angle grinder and noise will not differ in good performance.
Video: How to Disassemble a Reducer Angle Grinder Fiolent
In the next video, after disassembling the gearbox of another model, the Bosch angle grinder is observed significant grease contamination abrasive particles. Conclusion: an inspection of the internal cavity of the gearbox should be carried out regularly to avoid early failure of the power tool.
The author suggests replacement of expensive grease from Bosch, another cheaper and more affordable domestic. Important: the postulate that there is never too much grease is not acceptable here. A large amount of grease will cause it to be squeezed out through seals on the gear housing, for example, through the seal gland. Therefore, lubricants should be placed in the gearbox a strictly defined amount.
The following video details gear spindle disassembly process angle grinder of one of the Hitachi models. It is caused by replacing seized bearings, located in the gear housing cover. In order to reach it, the driven gear pressed onto the shaft should be removed. Due to the small distance between the gear and the gearbox cover, the puller lips are further developed by grinding their surface to the required thickness in order to get into this gap. Important: before pressing out the gear, it is necessary to remove the retaining ring fixing it.
A design feature of the DeWalt angle grinder is a gear housing design. The cover here does not carry any additional functions., in addition to protection against ingress of abrasive particles. The flange where the bearing assembly is located is made as a unit with the housing.
Usually when replacing a structural element (in this case, brushes) in most cases grease is replaced in the gearbox. To do this, the DeWalt angle grinder is completely disassembled with the rotor removed, so that it is convenient to wash and clean the gearbox cavity from old grease.
Another feature of the DeWalt angle grinder is driven gear design. A conical insert inside the gear case prevents operation during overloads. The preload force of the conical insert is adjusted to work at permissible loads. With increased effort, the gear will slip over the conical surface.
For convenience, when replacing oil, the author uses a dimensional syringe. It is easy to control the amount of grease required for refueling.
The following video shows gear inspection one of the models of grinders Makita. After a certain time worked full analysis angle grinder with rotor removal. Visually visible wear on the teeth of both gears, while there are chips. The author, unfortunately, did not analyze the reasons for their appearance. Replacing worn gears with new ones does not guarantee them continuous operation.
The Sparky angle grinder in the next video by shows the reason for one-way spindle rotation and a way to eliminate the defect. A collapsed rotor bearing with a support in the gear housing caused it to skew, which contributed to damage to the aluminum casing in the form of chipped chips. With the help of pullers and a wooden drift, the author quite easily copes with disassembling the gearbox and replacing both bearings on the rotor bearings.
The video shows a very reliable angle grinder from Lepse, which had a breakdown after ten years of operation. At the same time during disassembly a defect that is rare. The cause of the breakdown of the bolt fixing the pinion gear remained unknown by the author. Perhaps these are fatigue stresses from periodic loads. The repair method with a drill and sprocket deserves attention.
To identify the cause of the failure, the Fiolent angle grinder in the next video helped disassemble the gearbox. After carefully unscrewing the fasteners on the gear housing, it was visible large spindle play in the bearing support assembly. Parts of the bearing race confirmed the direction of repair work on replacing the collapsed support unit.
Reason increased noise angle grinder The author found out the dold in the next video. After disassembling the gearbox revealed large backlash in the bearing units. It should be noted that they did not affect the quality of the gear teeth in any way. they are in good working order. That is, if the gears are made of high-quality material in compliance with the heat treatment technology, they can work reliably in the most difficult conditions. Using the tool necessary for such repair work, the author shows how replace defective bearings.
A jammed spindle in a DWT angle grinder, which is described in the next video, repaired by a well-established technology. Detachable from brush rotor, so as not to be damaged in further repairs, disassembled gear. After that, visually check the wear of gears and play of bearing assemblies.
In this particular case, it is failed bearing caused malfunction Angle Grinder. The video shows how one defective bearing can lead to a whole loop of broken other parts. It is necessary to carefully monitor the condition of the bearing units, regularly check for the presence of backlash.
How to pull an anchor
Gearbox repair often requires its complete disassembly with the release of the rotor. In some types of models of grinders, this is not so simple. The following videos provide recommendations on how to use the inertial properties of the rotor for this purpose.
In the first video, the basis for the work is bench vise, and in the second from the corresponding square pipe a small fixture is made. After lightly tapping the gear case on the edge of a vice or pipe, the rotor is released from the gear. Which method is better is at the user’s choice.
How to replace bearings
In some cases, when spindle play is detected no complete disassembly required angle grinder with the release of the rotor. In the next video, where the Interskol angle grinder is repaired, it is enough to replace the spindle bearing units. the ball bearing from the working end of the spindle and the sliding bearing on the opposite side. The absence of backlash in the rotor bearing is estimated by the noise and vibration of the angle grinder (without spindle), placing its upper part in a plastic bag to eliminate the possibility of grease splashing during operation. detailed information on replacing bearings with angle grinders will be provided here.