Motor-roll gearboxes “Neva”: device and maintenance

Motoblocks of various sizes and firms (including TM “Neva”) became an indispensable assistant farmers and owners of large summer cottages. Reliability and efficiency of this device depends on its technical condition and proper care. Therefore, it is worth considering the basic principles of servicing the gearbox “Neva”.


The possibility of regulating the speed of rotation of the internal combustion engine is limited to the available working modes, therefore, in engine equipment (from motor-blocks to cars), devices traditionally are used to change the speed of rotation transmitted from the engine to one or another structural elements.

If in cars for this purpose, the gearbox is used, then gearboxes are traditionally installed on the Motoblocks “Neva”, allowing to control the speed of rotation, torque and movement direction. It is to this element that the wheels of the device are connected and various attachments, requiring connection to the engine (for example, a cultivator cutters, mowing blades, brooms and so on).

As arranged?

Despite the fact that the St. Petersburg Plant “Red October” produces a wide range of non-chill motoblocks “Neva”, characterized by power and complete, gearboxes in all these devices are arranged on a single general scheme. On the principle of operation, the gearbox used refers to the type of gear chains, where the change in the speed of rotation is carried out by the interaction of the system of the gear of different diameters and with various amounts of teeth, which are either in direct contact between themselves or are associated with a chain transmission.

This design combines the device used on the motorb blocks with a bicycle gear mechanism – slowing rotation is achieved by crossing the transmitting chain force on the gear with a large diameter. The difference lies only that in the gearbox, except for those on the same gear axis, also individual gears links, allowing to vary the speed and direction of rotation in broader limits, as well as transmit rotation simultaneously on the motor-block wheels, and the equipment used on it.

The entire system of chains, shafts and gears of gearboxes of Motoblocks “Neva” is placed inside a durable hermetic case made of aluminum. Lubrication of rotating parts is carried out by filling the product with oil (such a principle of the structure is called “oil bath”).

An important design feature of the gearboxes used on the “Neva” of the gearboxes is the presence of a mechanism of disagreement of wheel semi-axes, which allows you to transmit a torque only to one of the 2 wheels of the device. It makes it easier to maneuver.

The gear lever, as well as other elements for controlling the gearbox, are removed outside, which greatly facilitates its setting. Total 5 positions. When you click on the lever connected to it, the plug displays the transmitting rotation of the clutch from the gear with gears. When switching the lever, the plug translates the clutch to the desired position. When you let go of the lever, the coupling is enhanced with the gear system you need, and the plug returns to the initial position.In the standard operation mode, rotation is transmitted through the gear located near the input shaft of the device.

Connecting the drive to the right axis leads to a slowdown of the motoblock. “Drilling” gear shift knob leads to the transfer of the coupling to the left, larger gear, which leads to the inclusion of reduced transmission. This is useful when you need to develop a larger torque at a lower speed of movement.

Finally, the extension of the lever to the end leads to the inclusion of increased transmission, which allows you to develop a higher speed.

The dimensions used on the products of the Red October plant gearboxes are 23 × 30 × 61 cm, and their mass without oil does not exceed 18 kg. The volume of oil crankcase used to refuel the oil device is 2.2 liters.

The diameter of the shaft transmitting rotation from the device on the wheels is 30 mm.

An essential disadvantage of the design used in the gearboxes of the “Neva” design is the fact that it is necessary to disable the engine to switch the gear and wait for a complete rotation of the pulley device. Switching the gear “On the hot” can lead to a jam, breaking the chain or damage to the gear.

Basic rules for performing work

Any work on disassembling and assembling the gearbox, as well as its maintenance must be performed at a predetermined workplace with all the necessary tools. It must be ensured by the cleanliness of the workplace, which will eliminate the hitting of dust, dirt and garbage inside the mechanism. All work is desirable to perform in clean work gloves, which will ensure both the protection of the hands of injuries and pollution and the protection of the components of the gearbox from the ingress of unwanted garbage and dust.

Carefully follow the status of the tool used – It should not be noticeable damage, especially cracks. Failure to comply with this rule is fraught with dangerous injuries.

Before disassembling the gearbox, drain the oil from it. After that you need to carefully clean all parts of the device from possible contaminants.

After repairing and assembling the gearbox, be sure to fill in it fresh oil before operation.

Typical breakdowns and their repair

The most frequent breakdowns of the device are.

  • Oil leakage through the output shaft. To eliminate this problem, you need to change the seals installed in the gearbox. To replace them, you need to purchase new, dismantle the screwdriver installed in the gearbox, and then install new seals in their place. This will help strengthen the motoblock, the capacity of which is reduced due to constant oil leaks from the gearbox.
  • If leakage is observed through the switch shaft, then you may have flooded in a gearbox too much lubrication. Therefore, it will be enough to drain the surplus of oil and check whether it helped in troubleshooting. If the leaks continue, the replacement of the seals will help.

  • Circuit breaking, which leads either to the enclation, or to the inability to work the device on individual transmissions. To repair, you need to replace the torn chain to the new.
  • If the gearbox does not transmit a torque in any of the installed transmissions – most likely, there was a breakdown of one of the gears. After disassembly, you need to find a broken asterisk and replace it with a new one.
  • If the transmissions do not switch, you need to check the status of the fork, bushings and threads of the gear handle, and then replace the damaged element.

Expand the capabilities of the motoblock will help its upgrades by installing a full-fledged gearbox, for example, from a VAZ car, instead of gearbox.

How to choose spare parts?

If you want your motor-block to work steadily without the need for constant repair, be sure to purchase only new spare parts from official dealers. It is best to acquire spare parts to gearboxes in certified service centers and partner stores “Red October”.

Pay special attention to the type of oil you are going to pour into gearbox.

For devices used on the “Neva” motor blocks, the following marks of transmission oil are best suited:

  • TEP-15;
  • TM-5;
  • SAE90 API GI-2;
  • SAE90 API GI-5.

How to change the chain of the gearbox of the Motoblock “Neva”, look in the video below.

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