OPERATING MANUAL
Pneumatic rotary drive units type ST | DT
Wesa-Armaturen GmbH
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+49 (0)7181-404-0
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Operating manual
D-73650 Winterbach
Drive units ST | DT
Date of issue 10-2019
5.5.
Remove the O-rings from the side covers (note: if the servo drive unit is not relatively new, we
recommend that you replace all the O-rings on it, see Table 2A).
5.6.
Turn the pinion anti-clockwise (note: if it is a C installation model, the pinion must be turned in the
opposite direction) until the pistons have come free from the pinion so that they can be removed
by hand, see Fig. 4. If the manual removal of the pistons from the housing of the servo drive unit
proves difficult, the pistons can be pulled out using pliers (position them on the spring cups on the
piston). Ensure that the surfaces of the pistons are not damaged. When removing the pistons, note
the original position to ensure that the pistons are positioned correctly during reassembly.
Warning:
Never use compressed air to push the pistons out of the servo drive unit housing. Danger of
injury.
5.7.
Remove the locking ring (Seeger ring) and the washer on the ring from the pinion (top). Place the
servo drive unit on two wooden supports so that the pinion can be pushed easily from the top out
of the servo drive unit housing. Use a rubber or plastic mallet if necessary to tap gently on the upper
end of the pinion. Then remove the pinion from the bottom whole of the drive housing (Fig. 5).
Tables 2A and 2B show the spare part series of the slide elements and O-ring seals.
6.0. Installation of components
6.1.
Inspect all contact and wearing surfaces for wear or possible damage.
Note:
Ensure that all the parts are still within the tolerance specified by the manufacturer.
6.2.
Ensure that all the metal parts are clean and free of burr and chips.
6.3.
lubricate the interior of the cylinder chambers, the seats of the O-rings and the slide surfaces of the
pinion and pistons with MO-Bilux EP 2 or equivalent grease which is suitable for the temperature
range between -20° C and +130° C.
Note:
Special grease is required for operation in lower or higher temperatures. Please contact us direct
for further details. If the servo drive unit has already been used, we recommend that you replace all the
O-ring seals to ensure safe, perfect operation.
6.4.
Fit all the slide jaws and guide rings on the pistons and pinion, then fit the O-rings on the pistons,
housing cover and pinion.
6.5.
Insert the pinion into the servo drive unit housing. Fit the Delrin washer and the locking ring (Seeger
ring) to this upper part projecting out of the housing.
6.6
Insert the pistons into the cylinder housing until the racks are in contact with the pinion. Ensure
that the pistons are clearly aligned inside the cylinder housing, they do not jam and the pistons are
symmetrically positioned with the drive pinion in the connection.
