Reeves Drive Selection

For economical, correct Motodrive selection the following details should be ascertained:

1 – Load type and torque requirements

2 – Output speed range and power requirements

3 – Environmental conditions

4 – Application codes

5 – How load is to be connected to output shaft

6 – Mounting position (floor, wall, etc.)

7 – Power supply details (volts, hertz, single or three phase)

8 – Control type (handwheel, electric remote control, airtrol, electronic)

9 – Control position

10 – If other than normal duty, add-

Size and frequency of load

Hours of operation per day or week

Frequency of stops and starts

Inertia load

Frequency of reversal of rotation

11 – Tachometer calibrations if required

Power / Torque Characteristics

The true characteristic of the variable speed belt drive is neither constant torque nor constant power, it is a combination of both, illustrated thus:

torque curve






To simplify tabulation of the ratings the curves have been modified and are illustrated thus:

torque curve 2







In all cases the drive should be selected such that the maximum speed is above the speed N2cp as maximum power is only delivered above this speed.


To make the most economical selection it is necessary to determine the actual torque or power requirement and the speed range over which it is to be used.

Characteristics of the torque or power should be established.

a) Constant torque

b) Constant power

c) Combinations of (a) and (b)

d) Power varies with some function of speed

a) Constant Torque Application

constant torque






The diagrams illustrate typical power and torque curves for Motodrive and/or Motodrive/reducer combinations.  The constant torque line has been plotted on these curves.  The torque plot MUST be below the curve for the drive.

b) Constant Power Application

constant power






Again, the power requirement must be below the plot for the drive.

Types (c) and (d) should be referred to our sales office, quoting all details of the drive.