Hercus HK Series Operating and maintenance manual

HERCUS HK SERIES WORM JACKS
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MAINTENANCE AND OPERATING
INSTRUCTIONS
HK SERIES WORM JACKS
2 — 100 TONNES
PLEASE READ PAGE 5 FIRST
JULY 2006

HERCUS HK SERIES WORM JACKS
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HK SERIES WORM JACKS - OPERATING DATA
CAPACITY
Rated capacities of Jacks are maximum designed loads based on structural and
mechanical strength and should not be exceeded.
These loads assume intermittent and/or low speed operation which will permit
dissipation of heat.
When this is not the case the capacity of the Jack can be further limited by heat
build-up in the worm wheel nut.
Except for very low speeds Jacks are suitable for continuous operation only at
greatly reduced capacity.
Heat build-up in the nut can also become a problem when Jacks having very
long screws are traversed through their full stroke in one movement.
HIGH SPEED OPERATION
The maximum recommended input speed for HK series Jacks is 500 RPM
unless the Jack is operating for very short intervals and at reduced load.
For short term operation input speeds of up to 1800 RPM are acceptable for
loads not exceeding 25% of normal rated capacity.
SELF LOCKING
Hercus HK series Jacks are self locking and will not lower of their own accord
under steady load.
Where externally induced vibration is present this does not necessarily apply
and the Jack could creep down unless some other form of positive locking is
provided.
LIFT LIMITATIONS
For applications where the load screw is under tension the capacity of the Jack
is not limited by the length of travel. When the screw is under compression the
maximum allowable load is limited by the column strength of the screw.
SIDE LOADS
The HK series of jacks are intended primarily for raising and lowering loads and
side thrusts should be avoided or taken by guides wherever possible.
Any side thrust will reduce efficiency and accelerate wear.

HERCUS HK SERIES WORM JACKS
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OPERATING TEMPERATURE
Load and speed ratings for HK series Jacks are based on ambient temperatures
up to 80 deg.C.
The use of high temperature greases will permit this to be raised to 170 deg.C.
BACKLASH
Backlash in Jacks is an accumulation of clearance in the lifting screw,
the worm gearing and load bearings and must be sufficient to accommodate
lubricant and prevent binding under load.
The backlash present will vary from approximately 0.25mm in HK2T series
to approximately 0.50mm in HK20T sizes.
CONNECTION IN SERIES
For Jacks operating in series the number of units which may be connected in
line is limited by the torque capacity of the input shaft of the first Jack.
Where Jacks are operating at less than full load the number in series may be
increased proportionally.
LUBRICATION
HK Series worm Jacks are despatched packed with grease which under normal
conditions should be sufficient for six to eight weeks operation. In regular use
the Jack should be lubricated every six to eight weeks using one of the following
extreme pressure greases or their equivalent.
Shell Alvania EPI
Caltex Ultra Duty Grease 2
Ampol EPCI
Mobil Mobilux EP2
For very severe conditions the jack should be lubricated weekly with a
molybdenum disulphide grease in both the box and on the screw thread.
When Jacks are operating continuously or at high speeds lubrication must be
more frequent and it may be necessary to make some alternative arrangement
for lubrication of the screw thread.

HERCUS HK SERIES WORM JACKS
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INSTALLATION
When installing worm Jacks it is essential to ensure that they are securely
bolted on rigid mounts with proper support and adequate foundations.
Connection of input shaft and lifting screw should be checked for alignment.
Where mis-alignment is likely to pose a problem the input connection should if
possible be made through some type of flexible coupling.
Prior to starting up the installation should be cranked over by hand to ensure
freedom from binding.
Power operated installations should where appropriate, have limit switches,
visual travel indicators or safety stops to guard against over travel.
In addition a positive stop should be installed to prevent the lifting screw from
being ejected from the jack in case of accidental over travel.
When Jacks are to be used under conditions of stalled load a torque limiting
clutch or similar mechanism should be incorporated to guard against accidental
overloading.
MAINTENANCE
In service, Jacks should be checked regularly for cleanliness, damage and wear.
Load screw threads should be kept clean and lubricated and in dirty conditions it
is desirable that they be covered by protective boots.
Dust or grit should not be allowed to accumulate around working parts.
When not in operation Jacks should be left in the closed position if circumstances
permit.
Drive connections should periodically be checked to ensure continued alignment.
Linear backlash in the lead screw should be checked periodically for wear in the
worm wheel nut.
When wear in the worm wheel nut thread exceeds half of the thread thickness a
potential danger of shear failure under full load could exist and the nut should be
replaced.

HERCUS HK SERIES WORM JACKS
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OPERATION
CAUTIONS, HAZARDS AND NOTES
PLEASE READ FIRST BEFORE OPERATION
Prior to starting up the installation for the first time you should manually operate
the Jack Assembly by hand to ensure freedom from binding.
All installations should if possible have end Stop Nuts fitted. These nuts aid as
visual travel indicators and prevent the screw from over travel. If the worm screw
nut should fail, the stop nuts would prevent the screw from being ejected from the
worm jack assembly.
In all automatic and powered installations a positive stop arrangement should be
fitted at each end to prevent the stop nuts from making contact with the jack body
or jack mounting plates.
e.g. fitting of limit switches or stroke limiting devices.
When Jacks are to be used under conditions of stalled load a torque limiting
clutch or similar mechanism should be incorporated to guard against accidental
overloading and screw jack damage.
When self supporting bellows are used, never allow the stop nuts to compress
the bellows assembly against the worm jack or mounting plates. Damage will
occur to the bellows assembly and normal bellows operation may not be
possible. If this situation occurs, check bellows assembly before resuming normal
operation of worm jack assembly.
Keep worm jack and screw assemblies well lubricated at all times.

HERCUS HK SERIES WORM JACKS
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Part List
The above diagram demonstrates an average assembly, variations will occur
between different models.
e.g. 2 and 5 tonne Jacks do not have ‘worm cap open’ fitted as standard.

HERCUS HK SERIES WORM JACKS
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NOTES
Information contained in this manual should be used as a guide only.
Hercus reserves the right to change designs and specifications without notice.
CONTACTS
HERCUS PTY. LTD.
12 Camira Street
REGENCY PARK
SOUTH AUSTRALIA, 5010
Phone: [phone]
Fax: [phone]
e-mail: [email protected]
website: www.hercus.com.au