Operation & Service Manual (VA) 36 ST1175
Each column lift has a potentiometer that detects the height position and passes it
on to the control system. The control system controls and protects the lifting
system during raising and lowering in the following manner:
When there is a elevation difference of more than 5/8" and less than 1 1/4", an
extra correction valve in the hydraulic system opens until the elevation
difference between the column lifts is eliminated.
Lowering will be interrupted when the elevation difference is more than 1 1/4"
and less than 2 3/8". A lifting fork may be blocked. The cause of the fault must
then be traced. You can still lift and the correction valve in the hydraulic system
will open until the elevation difference has been synchronized.
When the elevation difference exceeds 2 3/8", the control voltage will be cut off,
causing all movement to stop. The cause of the fault must then be traced.
Height differences may be caused by oil leakage in cylinders or valves.
The control system is also designed so that:
Any column lift can be controlled individually.
Any pair of axles can be controlled individually; for an explanation, see chapter
Operation (on page 39).
Controlling individual column lifts and/or pairs of axles is exceptionally hazardous.
Refer to section Safety when hoisting.
The control is equipped with a number of programmable settings; see section
Programmable settings (on page 59).
4.5 Hydraulic power unit
The hydraulic power unit comprises an electrically powered pump, flow control
valves, control valves and a fluid reservoir.
4.6 Column, lifting cylinder and guide block
The column and lifting cylinder together form the most important part of the mobile
column lift. A guide block with rollers is located within the U-shaped profile of the
column. The rollers enable the guide block to move up and down the entire length
of the column. The lifting force is supplied by the hydraulic lifting cylinder.
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