GEARBOX SELECTION STEPS

SELECTION STEPS

STEP I – SERVICE FACTOR

Detail your application. How many hours will it operate each day? What are the characteristics of the driven load? The nature of the prime mover? Refer to Service Factor Tables* for application service factor.

STEP II – RATIO RANGE

Determine the minimum and maximum ratio and the number of intermediate steps.

STEP III – LOAD CHARACTERISTICS

If you need CONSTANT HORSEPOWER at all speeds select your unit at the maximum desired ratio. In this case, all ratios will have rating capacity greater than the design input HP.

If you need CONSTANT OUTPUT TORQUE at all speeds, select your unit at the minimum desired ratio. In this case, design input HP may exceed the HP rating capacity at the lower speeds.

STEP IV – DESIGN HORSEPOWER

Multiply the service factor in Step I by the actual input horsepower required to operate the driven equipment.

STEP V – UNIT SELECTION

Quick selection charts are provided here –  Quick Selection charts* for a general idea or you can use the method described below for a more accurate approach.

If you do not know the application torque requirement, calculate torque for your application assuming full motor HP, base motor speed and maximum reduction in the industrial gearbox using the following formula and calculator.

(HP X 63025) / RPM = Torque in in-lbs

Each of our standard industrial gearboxes are rated for a certain amount of torque as indicated in the individual product documentation.  These are guidelines and can be often modified by varying the components in the gearbox based on the application requirements.

Below is a quick reference chart for some of our models to give you a general idea of the size gearbox required based on the torque calculation above.

This is not a complete list.

Transmission SizeTorque Rating
E3725 in-lbs
2M570 in-lbs
5M980-2200 in-lbs
10M2200 in-lbs
20M4250 in-lbs
30M5430 in-lbs
50M7240 in-lbs
60M18000 in-lbs
55M40000 in-lbs
65M85000 in-lbs

Larger torque requirement require factory contact.

STEP VI – OVERHUNG LOAD

The overhung load on all shafts not direct-connected by means of a flexible coupling must be calculated.

Overhung Load = (HP x 63025)/(N x R)

“HP” = transmitted horsepower
“N” = RPM of shaft
“R” = pitch radius in inches of sprocket, pinion, sheave or pulley

Allowable overhung loads are listed in each unit rating table section. If unit does not have sufficient overhung load capacity, consider an outboard bearing support.

Note: To minimize reactions on shafts and bearings, be sure to mount sprocket, sheave, etc., as close to the transmission housing as possible.

STEP VII – SHAFT ASSEMBLY

Refer to the following Shaft Configuration PDF’s:

Shaft Location 20M, 50M, 55M, 60M, 65M – PDF

Shaft Location E3 – PDF

Shaft Locations 2M, 3M, 5M, 6M, 10M, 11M – PDF

STEP VIII – RATIO SELECTION

Determine the ratios necessary for required output speeds. Nominal ratios are listed for each unit size. Since each total ratio is achieved by combining two gear sets (except for the E3 transmission which uses only one gear set per ratio) there may be limitations on the ability to provide specific intermediate ratios, Please include allowable ranges with each inquiry.

It may also be necessary to provide a 4-speed transmission to achieve 3 specific ratios, a 6-speed to achieve 4 specific ratios, etc.

Note: Due to the large number of possible ratio combinations for each unit size, it is not practical to list them all on the Web site. Please contact Turner Uni-Drive for answers regarding specific ratios.