If the crane fails to hold or lift its seated load, it could be the result of one or a combination of
several problems. All parts referenced are shown in jack breakdown. Remove jack from crane
for all service work.
A. Control Valve (Item 30) – Turn jack upside down. Remove valve stem by turning
counter-clockwise. Inspect valve for wear or nicks. Replace if necessary. If stem
appears to be smooth, inspect seat for chips, dirt, or other forms of contamination.
Remove if necessary.
B. Pump Valves – The valves and valve seats must be clean and in mirror condition.
Dirt will sometimes find its way between the valve and valve seat, preventing a
tight seal between the two.
1. Inspect pump valve by first opening the control valve (Item 30). Remove
plug (Item 8). Carefully remove the pressure seal (Item 9) by using a small
dull tool. Be careful not toe rupture the body of the seal. The springs and
balls may be removed by tipping the hydraulic unit on its side so that the
parts fall out.
2. Place the jack on its side with the pump valve holes up. This will prevent
the fluid form running out.
3. With the aid of a light, inspect the valve chamber for dirt or other
contaminations. Ball seats must be free from nicks or scratches. If the seas
are deformed, the jack should be taken to a qualified service depot for
correction. Balls and springs must be clean and free from dirt, corrosion,
nicks, scratches, or other forms of damage.
4. If all parts appear to be in good working condition, use air pressure to blow
out any unseen dirt particles before reassembly.
5. Reassemble in reverse order of disassembly.
Check oil level and bleed air from the system before using. With control valve open and ram
retracted place jack in an upright position. Remove filler screw (Item 40). The oil level should
e level with filler screw opening. If oil is not at this level, fill reservoir with hydraulic jack
oil. (SAE #10) non-detergent motor oil or equal). DO NOT USE HYDRAULIC BRAKE
FLUID. If there is too much oil in the reservoir it will run out when filler screw is opened.
The air space above the filler screw is necessary to prevent a vacuum from forming at the top
of the reservoir. After correcting the amount of fluid in the reservoir, replace the filler screw.
Leave the control valve open and pump the handle a few times. This will bleed air form the
hydraulic system.
JACK SERVICE INSTRUCTIONS
12
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