Power Jacks EMA Actuators - Manual (Page 10)

EMA Linear Actuator
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10
6. Adjusting the Clutch
The clutch is a device mounted on the actuator inner tube (ram) which will slip when the
torque to drive the load exceeds the limit set. (refer 6.1)
The clutch spindle, (6) that is attached to the load via an end fitting, is supported on
bearings (8) and clamped from rotating by interlocking conical rings (7). The clamping
load is applied by a locknut (5) with keyways to engage a tab washer (4). The clutch
housing (3) is attached to the inner tube (1) and the clamping effort of the conical rings
(7) carries the residual torque of lifting to the clutch spindle (6).
If the load is axially locked or if a torque greater than the clutch setting is required to
move the load, the conical rings will rotate within each other, disengaging the spindle to
inner tube drive and preventing the motor from overloading the actuator components or
the load guides etc.
Under normal operation and with no overload experienced the clutch requires no regular
maintenance or adjustment. If however the clutch slips regularly in operation the setting
of the clutch will reduce to a point where the normal operating torque will overcome the
clutch and the load will not move. Under these circumstances the clutch can be adjusted
as follows:
1.
Remove the actuator from the installation.
2.
Extend the inner tube (1) and clamp in soft jaws in a vice.
3.
Bend out the tab of the washer (4) from the keyway of locknut (5).
4.
With a suitable fitting screwed on to the clutch spindle (6) tighten the locknut until
a torque is indicated in table 1 (refer 6.2) is measured, e.g. Clutch lever forces in
table are for a 254mm (10in) lever inserted through clevis.
5.
When the torque has been set, bend a tab of the washer into an adjacent keyway
in the locknut. The actuator is ready to reinstall.
6.
The clutch is selected from either of the following:
a)
Ringspan Cone Clamping Element TLK 250:-
i)
4202015.001 - 27Nm max.
ii) 4202025.001 - 74Nm max.
7.
When assembling the clutch a small quantity of oil (3 in 1) should be
applied to the cone (7) surfaces.