If the crane fails to hold or lift its rated load, inspect and repair using the following
information. 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 occasionally builds up 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 to rupture the body of the
seal. The springs and balls may be removed by tipping the hydraulic
unit on its side.
2. Place the jack on its side with the pump valve holes up. This will
prevent the fluid from running out.
3. With the aid of a light, inspect the valve chamber for dirt or other
contamination. Ball seats must be free from nicks or scratches. If
the seals are deformed, the jack should be taken to a qualified
service depot for repair. 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 dirt particles before reassembly.
5. Reassemble in reverse order.
Check oil level and bleed air from the system before use. With control valve open and
ram retracted, place jack in an upright position. Remove filler screw (Item 40). The
oil level should be 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 from the hydraulic system.
JACK SERVICE INSTRUCTIONS
12
