Power Jacks S-Series - Manual (Page 4)

4
Sym-metric Series – Screw Jacks
3 General Instructions
3.1 Maintenance and Installation recommendations.
I n order to ensure that the actuators give good service over a period of years the following precautions should be
taken
3.1.1
Select an actuator which has a rated capacity greater than the maximum load that may be imposed on it.
3.1.2 The structure on which the actuators are mounted have ample strength to carry the maximum load, and
should be rigid enough to prevent undue deflection or distortion of the actuator supporting members.
3.1.3 It is essential that the actuators be carefully aligned during installation so that the lifting screws are
vertically true and the connecting shafts are exactly in line with the worm shafts. After the actuators,
shafting, gearboxes, etc., are coupled together it should be possible to turn the main drive by hand. If
there are no signs of binding or misalignment, the actuator system is then ready for normal operation.
3.1.4 The actuators should have a greater raise than is needed in the actual installation. Should it be
necessary to operate the actuators at the extreme limits of travel it should be done cautiously.
3.1.5 It is important that the lifting screws should not be closed below the specified closed height dimension of
the actuators, otherwise serious damage may result to the worm gear. Lifting screw end stops are to
prevent over-travel or loss of screw. These are not load supporting and should be treated as an
emergency device only and must not be allowed to come into contact with the worm gears during normal
working cycles otherwise serious damage will result to worm gears and bearings.
3.1.6 The maximum worm shaft speed for these actuators should not exceed 500 R.P.M. for heavy loads.
Refer to Power Jacks Limited for higher worm shaft speeds for lighter loads. Absolute maximum is
3000rpm provided Power Jacks have advised acceptable.
3.1.7 The lifting screws should not be permitted to accumulate dust and grit on the threads. If possible, lifting
screws should be returned to the closed height position when not in use.
3.1.8 A periodic check of backlash between lifting screw and worm gear is recommended to check wear
on internal threads of worm gear. Backlash in excess of 50% thread thickness indicates that a
replacement will be necessary to replace the worm gear and nut assembly.
3.1.9 The actuators are shipped with the gearbox housing oil filled (unless otherwise required) to the correct
level and with the lifting screw packed with grease. This should be sufficient for normal operation. For
normal operation the oil level should be checked to read the correct level and the lifting screw lubricated
with grease once a month. For lubrication use one of the recommended lubricants (refer Tables1 & 2)
3.1.10 For severe service conditions the actuator should be lubricated with a molybdenium disulphide type of
grease daily or weekly depending on the conditions. If duty is heavy, an automatic lubrication system is
strongly recommended. If ambient temperature exceeds 90°C (194°F) consult Power Jacks.
4 Recommended Lubricants
TABLE 1 – GEARBOX OIL TABLE 2 – LIFTING SCREW GREASE
Manufacturer Lubricant Manufacturer Lubricant
BP Energol GR-XP150 Shell Alvania WR2
Shell Omala Oil 150 BP Energrease LC2
Castrol Alpha SP150 Castrol Spheerol L-EP2
Mobil Gear Oil 629 Mobil Mobilux EP2