Reducing gears

The reducing gear is intended for the speed-down and increase of torque. Every reducing gear has high-speed (input) and low-speed (output) shafts.

Reducing gear of general engineering application – this is the reducing gear which answers technical requirements, general for most cases of application.

Thanks to theirs universality the reducing gears of general engineering application are successfully used in lift-and-carry, logging machines, metallurgical and coal-face winning equipment, power-plant industry, building industry, oil and gas industry, agricultural machinery and process industry.

In accordance with GOST 16162-78 to the reducing gears of general engineering application there are referred:

• single, double reduction and three-stage parallel-shaft reducers;
• single and double reduction parallel-shaft planetary reducers;
• single-reduction right-angle reducers;
• double reduction and three-stage two-stage right-angle reducers;
• single and double reduction worm and enveloping reducers;
• double reduction two-stage worm speed reducers.

Consumer characteristic of the reducing gears of every type are determined by following main parameters:
• kinematic characteristic – gear ratio (speed of output shaft);
• power characteristic – torque and accepted overhung load on the output shaft;
• coefficient of efficiency.

For the reducing gears of general engineering application there are characteristic:
• high engineering level by mass-overall parameters and by torque value carried out by the reducer of specific standard size;
• conformity of part's design and level of theirs unification with specifications of large-scale manufacture;
• high economic efficiency and also maximal satisfaction of customer's needs (the most important characteristic by the rating of design it should be considered the coefficient of cost per unit, i.e. cost for the manufacturing and maintenance related to a workable torque).

The reducing gears of general engineering application are intended for operating conditions mentioned in GOST 16162-78. In areas with moderate climate - version У, with dry and humid tropical climate - version Т, categories of placing 1-4 according to ST SEV 458-77.


The reducing gears are classified by several features, the most important of them there are: type of used gears, quantity of stages, positional relationship of axes and theirs attitude, manner of fastening and others. At that the type of gear is the most principal classification characteristic.

Types of reducing gears:
• parallel-shaft reducer;
• right-angle reducer;
• worm reducer;
• planetary reducer;
• combination reducer.

Parallel-shaft reducer is applied for the transfer of rotary motion between parallel or coaxial shafts. These reducers have a high coefficient of efficiency (0,94…0,98 in one stage) and a significant operating life.

Right-angle reducer is more complex as compared to the parallel-shaft reducer. These reducers are applied for the transfer of rotary motion between crossing (as a rule at right angle) shafts. Theirs coefficient of efficiency is some less (0,9…0,96 in one stage).

Worm reducers are applied for the transfer of motion between crossing (as a rule at right angle) axes. One of important advantages of the worm reducers is possibility to get a large reduction ratio in one stage (to 80 in the reducers of general application and to a few hundred - in the special reducers). These reducers have a high ride comfort and noiselessness in work and self-braking by defined reduction ratios, this makes it possible to except braking gears from the drive.

Planetary reducer has evident advantages as compared to the normal parallel-shaft reducer. This is small specific materials consumption by sufficiently large output capability, this explains by the availability of multipair toothing; compactness, noiselessness, lesser mass and overall dimensions, possibility to get large reduction ratios (to a few tens of thousands) etc.

Combination reducer – this is the reducer with various combinations of gear types. For example, there is two-stage right-angle reducer, two-stage worm speed reducer, parallel-shaft worm reducer. The last stage can be planetary.