Wood’s Powr-Grip MRPT89ACO - Manual (Page 26)

Rev 13.0/2-13 24 MRPT89ACO: #35061
V
ACUUM
S
WITCH
A
DJUSTMENT
Vacuum Switch Function
A vacuum switch controls the vacuum lift light for an AC lifter (see OPERATING FEATURES for location of
vacuum switch). After the lifter attains a vacuum level sufficient for lifting the maximum load weight
(hereafter, “minimum lifting level”), the vacuum switch automatically turns on the lift light. When vacuum
decreases to a level that is lower than the minimum lifting level (as when releasing a load), the vacuum
switch automatically turns off the lift light again, until the minimum lifting level is regained.
Conditions Requiring Readjustment
At the factory, the vacuum switch is set to the minimum vacuum level specified for Load Capacity (see
SPECIFICATIONS). However, shipping vibrations or shocks, normal wear, or other conditions may
adversely affect this adjustment. Periodically verify the switch adjustment by comparing how the vacuum
lift light functions in relation to the vacuum level registered on the vacuum gauge, as follows:
• If the lift light turns on before vacuum attains the minimum lifting level, it is likely that the air filter’s
element is dirty. Any filter element that obstructs airflow must be replaced (refer to A IR
F ILTER M AINTENANCE preceding). Otherwise, the lift light would turn on at vacuum levels that are not
sufficient to lift the maximum load weight.
• If the lift light does not turn on after vacuum increases to a level much higher than the minimum lifting
level, the light bulb may be burned out. If this condition persists after the bulb has been replaced, the
vacuum switch may need to be adjusted to turn on the lift light at a lower vacuum level. Otherwise,
the operator might wait unnecessarily for the lift light to turn on, after the lifter has already attained
sufficient vacuum to lift the maximum load weight.
• If the lift light does not turn off before vacuum decreases to a level lower than the minimum lifting level,
the vacuum switch must be adjusted to turn off the lift light at a higher vacuum level . 16
Otherwise, the lift light would remain on at vacuum levels that are not sufficient to lift the maximum
load weight.
Adjustment Procedure
1) Using a 1/4" open-end wrench (as provided), turn the adjustment screw about
1/6th turn at a time (approximately one flat of the screw head).
To make the vacuum lift light turn
on at a lower vacuum level, turn the screw
clockwise (when viewing vacuum switch from end with electrical connectors).
To make the lift light turn off at a higher vacuum level, turn the screw counter-
clockwise (when viewing vacuum switch from end with electrical connectors).
2) Recheck the vacuum switch setting following each 1/6th turn of the
adjustment screw. In order to test the adjustment accurately, release
the vacuum pads completely before reapplying them to a test surface.
When the vacuum switch is adjusted correctly, the lift light turns on only
after vacuum increases to a level higher than the minimum lifting level; and the lift light turns off
again before vacuum decreases to a level lower than the minimum lifting level.
16
In order to observe lifter functions while vacuum is decreasing, it may be necessary to create a controlled leak in the vacuum
system (e.g., by breaking the seal between one or more vacuum pads and the test surface).
1 ELECTRICAL CONNECTORS
2 ADJUSTMENT SCREW
3 LIGHT OFF AT HIGHER VACUUM
4 LIGHT ON AT LOWER VACUUM