How To Put The Gear On The Trimmer
Owners of home workshops have many devices and devices that greatly facilitate manual labor and increase work efficiency. One such mechanism is a reduction gear. It is mainly used so that the rotation speed of the output shaft changes in a smaller direction or the torque increases on it. By design, this device can be combined, worm or gear, as well as single and multi-stage. Many do-it-yourself gear reducers do it yourself.
What is a gearbox?
This mechanism is a transmission link, which is located between the rotational devices of the electric motor or internal combustion engine to the final working unit.
The main characteristics of the gearbox are:
- Transmitted power;
- Number of driving and driven rotational shafts.
To rotary devices of this mechanism fixed gears or worm gears, which transmit and regulate movement from one to another. The housing has holes with bearings on which the shafts are located.
Necessary materials and tools
The following materials and tools may be required to make the gearbox:
- Wrenches and screwdrivers of various shapes and sizes;
- Files, drills;
- Rubber gaskets;
- Washers, pipe cuts, gears, bolts, bearings, pulleys, shafts;
- Vernier caliper, ruler;
- Vise, hammer;
- Frame from an old gearbox or steel sheets.
How to make a gearbox with your own hands?
The most important part of the reduction gear is its housing. It must be designed and manufactured correctly by one’s own hands, since the relative position of the shafts and axles, the alignment of the seats for the thrust bearings and the clearances between the gears depend on this.
Industrial Gear Housings made mainly by casting from aluminum alloys or cast iron, however, at home it is completely impossible to do. Therefore, according to your needs, you can pick up or finish the finished housing or weld from a steel sheet. Only in this case, it should be remembered that in the welding process the metal can “lead”, and therefore, to maintain the alignment of the shafts, it is necessary to leave an allowance.
Many masters do differently. In order not to bother with boring work, they begin to weld the body completely, and pipe sections are used instead of bearings, which are set in the required position and only after that they are finally fixed in place by welding or bolts. To facilitate maintenance of the gearbox, it is necessary to make the upper cover removable at the housing, and the drain hole, which will be used to drain the used oil, from below.
The gears are supported by the axles and shafts of the gearbox. Typically, in a single-stage mechanism, only shafts having a rigid attachment of gears are used. Both gears in this case rotate together with their shafts. The axis is used when it is necessary to insert an intermediate gear into the gearbox. It starts to rotate freely on its axis with a minimum clearance, and so as not to move sideways, it is fixed with a nut, thrust collar or retaining split washers. Shafts should be made of steel, which has good strength and is remarkably machinable.
The bearings for the shafts are bearings in the gearbox. They perceive the loads that arise during the operation of the mechanism. The reliability and operability of the gearbox depends entirely on how correctly the bearings were selected.
For a do-it-yourself mechanism it is best to choose sealed bearings, for which minimal maintenance is required. They are greased. The type of bearings depends on the type of load. When using spur gears, ordinary single or double row ball bearings will be sufficient. If helical gears or worm gears are present in the mechanism, an axial load begins to be transmitted to the shaft and bearings, which requires a ball or roller angular contact bearing.
Another quite important part of the gearbox are gears. Thanks to them, you can change the speed of the output shaft. To make gears, special metal-cutting equipment is necessary, therefore, to save money, you can use finished parts from decommissioned devices.
It is very important in the process of mounting gears to set the correct gap between them, because the level of noise that occurs during gear operation and the load capacity depend on it. It is best to lubricate the gears with liquid industrial oil, which is poured so that it covers the teeth of the lower gear. The remaining parts are lubricated by spraying oil on the internal cavity of the mechanism.
Shaft oil seals prevent oil from leaking out of the gearbox. Install them on the outputs of the shafts and fasten in the bearing caps. To prevent accidental destruction of parts of the mechanism from heavy loads use a safety clutch. It comes in the form of a bellows, spring-loaded friction discs or a shear pin. Installation process bearing caps very easy, which are end-to-end or deaf. They are selected from finished parts or turned on a lathe.
This mechanism is indispensable helpers in various fields of human activity. Usually it is used:
- In industry;
- In automobile gearboxes;
- In electrical equipment and household appliances;
- In the gas industry and many other industries.
In industry, this mechanism is used very widely. In various processing machines it is used as a rotational transmission part, increasing speed of revolutions.
But in automotive gearboxes, the gearbox, on the contrary, lowers the engine speed. The smoothness and softness of the transport depends on how well its adjustment is debugged.
This speed-reducing device is also used in household appliances and electrical equipment having electric motors. It can be mixers, washing machines, drills, food processors, angle grinders.
Gearboxes are an indispensable part of ventilation equipment, treatment facilities, pump systems. They are contribute to maintaining optimal gas pressure in gas-flame installations.
The gas industry also cannot do without this mechanism. Transportation and storage of gases is a rather dangerous process, so they use a gearbox, with which they block the gas access or open an outlet for it, regulating the pressure.
Assembling the gearbox with your own hands from improvised means is a rather troublesome business, but not too difficult. With its help, the rotation of the output shaft decreases and its torque increases. The performance of devices or machines depends entirely on this part. This mechanism is used in the most diverse fields of human activity.
Sometimes, in the midst of intense grass mowing operations, your trimmer begins to make unpleasant, grinding sounds. This complains about the lack of lubrication of the gearbox. The most intensively loaded unit of the device. And soon, these “warnings” may be followed by jamming of the drive
What grease should be used for the trimmer gearbox?
In the process, the mechanical part of the trimmer is loaded with contact forces on the teeth, resistance reactions from adhering grass (sometimes with dirt), dynamic, impact loads due to constantly changing torque. The grease for the trimmer gear must fully take into account these features, so the selection of the brand must be strictly individual.
The following factors are taken into account:
- Brand of the manufacturer. Each brand is not unreasonably oriented on lubricants of its own manufacture (you can talk about cheap Chinese products later). This applies to manufacturers such as Husqvarna, Stihl, Huter, Makita, etc. The exception is domestic trimmers: for example, Caliber in the user manual does not indicate the brand of lubricant at all
- The viscosity of the lubricant. As you know, all lubricating compounds are divided into three groups. Highly viscous (colloidal systems containing various additives), plastic compounds of universal use and solid lubricants that soften during operation.
- Good adhesion to the surface of the gearbox parts, as a result of which the grease is not squeezed out into the gaps or out of the assembly.
- Gearbox lubricant consumption rate. Here you have to rely on your own experience and the recommendations of specialists, since some trimmer manufacturers, relying on the availability of their own service centers, generally do not give clear recommendations regarding the period of operation of the gearbox between two lubrications.
The lubricant consumption also depends on the temperature at which it retains its lubricity. When the gearbox is heated to 40 ° C, it is considered that its operating conditions are satisfactory, and there is enough lubrication.
It is believed that there is no universal lubricant for the trimmer gear, but this is not entirely true. In fact, a suitable lubricant will be one in which the following components are present:
- Anti-wear additives containing no toxic lead;
- Solid lubricants with the presence of graphite or molybdenum disulfide (the latter is preferable, since the lubricity is fully preserved for a wide range of shaft revolutions);
- Only mineral (inorganic!) Oils with a high degree of purification.
These requirements are fully met by Gear Grease OREGON or Champion EP-0 lithium greases, domestic compositions Oleo-Mas, Litol.24, or Azmol 158, as well as those recommended by the manufacturer of a particular trimmer model.
How to lubricate the trimmer gear?
In the upper part of the housing, where the gear block is installed, there is a technological hole, which, when the trimmer is operated, is plugged with a screw. This screw is unscrewed, and 1.5 2 ml of grease is introduced into the hole using the nozzle on the tube. If the lubricant was purchased in a different packaging, then for this operation, a regular disposable medical syringe is also suitable.
After that, the screw is installed in its original place. This procedure, regardless of the user’s recommendations, should be performed every 10 15 hours of operation of the trimmer in operating mode. Other reasons for updating or replacing the gearbox lubricant are independent minor maintenance work (for example, cleaning and washing the gearbox gear before the summer season), repair of the unit, preservation of the trimmer for the winter period, etc.
If the gear unit is disassembled, it is recommended to completely remove the remains of the previous grease from the surface of the parts, even if it does not have any signs of oxidation and contamination. And only then apply new grease. After applying the lubricant, it is recommended to turn the shaft manually several times, and make sure that the lubricant is evenly distributed over all parts of the gearbox.
When lubricating, special attention is paid to the following elements:
- Flywheel: on its surface, as a rule, the remnants of grass adhere intensively, and thickened grass juice creates additional resistance.
- The starter coil dog, which is constantly in contact with the grooves on the flywheel when the drive is turned on. In this case, not only mechanical wear occurs, but also mechanochemical corrosion of the flywheel-dog joint, since the materials for this pair are different (the flywheel is aluminum and the dog is steel).
- Bearings, if their seals are worn, and through them the grease is squeezed out. In this case, the unit begins to vibrate intensively when loaded. This happens with Chinese-made trimmers, so it’s worthwhile in the future to think about replacing the bearing assembly with a better one, for example, from the Swedish company SKF.