GearCutting Company Ltd - Power Transmission

Power Transmission

  • Suitable for in-line coupling mode or sprocket and pulley drives.

  • Micro switch actuation by striker pin.

  • Stepwise adjustment of maximum Torque.

  • Torque range from 11 to 113 Nm (100 to 1000 lb-in).

The torque limiter consists of two co-axially mounted members locked together by a cluster of spring loaded balls acting as slideable links between the two halves of the unit. Overload forces the balls out of their seats which continue a ratchetting motion until relative rotation between the two halves disappears.

One of the ball pockets contains a spring loaded pin slightly protruding from the face of the torque limiter. When slip occurs, the pin acquires a reciprocating motion of 2-3 mm stroke and may be used to operate a switch or any warning device. In addition, slip is accompanied by a whirring noise which acts as an audible warning.

The outside diameter of the drive ring is ground to size and its face contains threaded drive holes and a location spigot. Thus, either a sprocket or a pulley may be bolted to the drive ring, ensuring that the resulting side load is carried well inside the bearing.

LO Series dimensions

SIZE: LO12 LO19 LO30 LO40
Max. torque (Nm) 11 28 56 113
Max. torque (lb-in) 100 250 500 1000
Pilot bore 6 8 10 12
Max bore d 12 19 30 40
A 38 51 80 102
B 19 25 39 54
C (F6) 37.5 50.5 75.5 101
D (F7) 25 36.5 57 77
E 1.5 1.5 1.5 1.5
  2 X 4 X 4 X 4 X
Securing holes (Dia X PCD) M4 - M5 - M6 - M8 -
  31.25 43.5 66.5 89

LO Series Power Transmission
Torque limiters leave the factory with a full complement of springs and securing screws. The graph below shows, for each of the four sizes, the variation of torque with a diminishing number of springs. Torque variation may thus be obtained by removal of springs and not by tightening or slackening of the screws. It is important to remember that when replacing springs, the securing screws must always be flush with the face of the torque limiter.

Selection and Torque Adjustment

Reduction in the torque setting of LO type limiters is obtained by progressive removal of springs in accordance with the table below:

Torque Step/Spring (Nm) 1.8 4.7 5.6 11.3
Max. number of springs 6 6 10 10

For example an LO30 limiter with 10 springs fitted would give a torque setting of 56 Nm and removal of one spring would reduce the setting to 50.4 Nm.

The torque limiters are available with an accurate and concentric pilot bore, without a keyway. A locking set screw is provided. Larger bores and keyways are available to order. Trip plates for micro switches are also available on all series.