Reliable homemade gear for motoblock

The motor-block serves as an indispensable assistant in the processing of small land plots. You can not buy such a useful device, but make it yourself. A person who knows how to work with iron is quite capable of making not only the undercarriage, controls, but also self-made gearbox for the motoblock, and attachments.


Motoblock is designed for work related to the cultivation of land, at least for the transport of small loads over short distances.

Motoblock is designed for work related to the cultivation of the land, occasionally transportation of relatively small loads over short distances. The parameter reflecting the performance and scope, is the engine power. Distinguish light tillers with engine power up to 1-5 horsepower (hp) and heavy, which can stand engine up to 10 hp

Attachment determines the nature of the operations performed. According to the method of attachment distinguish:

  1. Motor-cultivators - working tools are installed on the leading axis of the engine through a reducer, the tractive effort is carried out due to the active rotation of these tools.
  2. Wheel tillers - attachments mounted on the bracket-holder, traction force is carried out by the drive wheels.

Purpose and types of gearboxes

Scheme of the angular gear motorblock

Diagram of the angular reducer of the motor-block: 1 - lock ring, 2 - adjusting ring, 3 - bevel gear, 4 - adjusting rings, 5 - bearing, 6 - intermediate gear shaft, 7 - upper housing, 8 - output shaft, 9 - adjusting rings , 10 - bearing, 11 - bevel gear, 12 - locking ring, 13 - anther cup, 14 - anther, 15 - cuff, 16 - adjusting rings, 17 - lower body, 18 - adjusting gasket, 19 - bearing, 21 - cover , 22 - gear, 23 - gear, 24 - shaft.

An important element of the design of the motoblock is a gearbox. It transmits torque from the motor shaft to the working tool or wheels of the unit, depending on the design. Due to the special features of the device, the torque is not simply transmitted, but amplified with a simultaneous decrease in the number of revolutions of the driven shaft.

By design, gearboxes can be of several types:

  1. Gears The gearbox is a shaft with cylindrical and bevel gears mounted on them. By design, gear reducers can be implemented in a direct pattern (the moment is transmitted through a cylindrical gear) and angular (to transfer torque from the output shaft directly to the gearbox bevel gear is used).
  2. Gear worm. Used with vertical engine crankshaft. The gearbox consists of a worm gear and a worm (metal screw with a coarse-step rectangular thread). A feature of this gearbox is the transmission of rotation at an angle of 90 °.
  3. Chained. The torque from the engine to the shafts of the gearbox is transmitted by a metal chain that rotates the sprockets.
  4. Belts. It is an analogue of the chain method with the only difference that instead of a chain a V-belt or a rectangular belt is used, and instead of asterisks there are pulleys with profile grooves for holding the belt.

In the design of a motor cultivator, angular gear-worm or chain gearboxes are often used. Gearbox gearboxes are used in the construction of powerful units. Belt transmission method is quite rare, because belts are believed to be prone to clipping and slipping from their seats.

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Preparatory work

Motoblock device

The device tiller.

In the manufacture of self-made motoblock, before proceeding to the manufacture of the gearbox, it is necessary to make at least an approximate calculation.

Based on the calculation data, you can evaluate:

  • gear ratio;
  • gearbox type;
  • torque values;
  • shaft loads;
  • overall dimensions of transmissions (depending on the type of gearbox selected).

You can make a self-made motoblock with a gearbox that works according to different principles. However, most often in homemade units used gearboxes with chain transmission. This is due to a compromise combination between the availability of component materials, the reliability of their work and the relative ease of assembly.

For the manufacture will need:

  • sprockets with a pre-calculated number of teeth, providing the required gear ratio;
  • driven shaft;
  • bearings of the required size for installing the drive and driven shafts;
  • chains of necessary length;
  • metal corners for mounting the protective case;
  • protective housing (housing).

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Gearbox assembly: recommendations

The assembly process begins with the installation on the output shaft of the engine leading sprocket first stage gear.

Diagram of the device motoblock gearbox

The scheme of the device gear motorblock.

The method of fastening the sprocket can be very diverse. Depending on the shaft design, the sprocket can be fixed on it with a key, a flange, or even fastening with the help of spot welding is sometimes encountered.

The driven shaft of the gearbox can be assembled from two semi-axes. The flanges must be machined at the ends of the semi-axes. The driven sprocket of the second stage is inserted into its seat between the flanges, and the semi-axes are assembled into a single unit with the help of a bolted joint.

If possible, you can do a little easier without the use of axle shafts and bolts. To do this, a whole shaft is machined on a lathe. The shaft will be fixed with a key or if necessary welding. A significant disadvantage of this method, compared with the previous one, is less reliable and accurate fastening of the sprocket.

Diagram of the device and the gearbox

Diagram of the device and operation of the reducer: a - gas does not flow through the reducer, b - gas passes through the reducer, 1 - fitting, 2, 3 - pressure gauge, 4, 8 - springs, 5 - valve, 7 - diaphragm, 9 - screw, 10 - chamber, 11 - valve.

In order to protect against the ingress of dirt and foreign objects into the chain transmission, the second-stage gearbox unit is placed in a protective housing. In addition to the transmission protection function, the housing is a reservoir for lubricating fluid, which ensures smooth operation and reduces wear on rubbing parts.

In the body of the housing should be provided coaxial landing slots, in which the bearings are installed, which serve as a shaft support. To install the driven shaft, ball bearings are used in a conventional cylindrical housing. The drive shaft is mounted on bearings with eccentric housing.

Due to the peculiarities of its design, the eccentric can change its position in the landing slot at an angle of up to 15 °. Together with the bearing will change its position and the drive shaft, thereby adjusting the value of the chain tension, if necessary.

During operation, the teeth of the driven sprocket of the second stage of the gearbox are immersed in oil poured into the housing. The rotation of the mechanism provides a uniform distribution of lubricating fluid at the nodes of the chain transmission.

The tightness of the casing can be achieved by installing on the seats of the bearings and along the detachable line of the housing standard sealing gaskets and seals. Bearing seals are easy to pick up, because all sizes in this case are standardized and interrelated.

In the case of sealing the case, the situation is somewhat more complicated. In the case of using a non-standard product or case from any old models of gaskets, it is rather difficult to find. The solution may be the use of specialized oil-resistant sealants.

With the correct calculation and accurate assembly of all parts of a homemade motoblock, the unit will not be inferior to its factory counterparts.

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