JCB JS130WJS145WJS160WJS175W Hydraulic Rams Fault Finding
The chart below lists some possible problems and suggested remedies. The types of problems fall into four main categories as follows:
1 Oil leakage from piston rod sliding part.
2 Oil leakage from cylinder head joint.
3 Oil leakage from pipe and cylinder tube welds.
4 Faulty operation
|1||Piston rod sliding part oil leakage||Piston rod||On the sliding surface, there are scratches and rust that can be felt by the fingernail. The plating is peeling.||1 Use an oil stone and remove the scratch and make the sliding surface smooth. If oil leakage continues even though the rod surface is made smooth, the scratch may havedamaged the U-ring and other seals, so dismantle and inspect. 2 If the scratches and rust cover such a wide area that they cannot be repaired by an oil stone, renew the piston rod and U-ring, wiper ring and seals and the piston rod bearing member. Re-plate or renew the piston rod. Also inspect the seal and piston rod bearing member and renew if damaged.|
|Rod packing (Buffer ring U-ring)||Foreign matter is biting into the inner and outer surfaces of the packing. There is a scratch on the inner surface. The lip and groove parts are locally carbonized (burned).||Remove foreign matter. If there is damage to packing, renew it. Renew. Possibly due to burning caused by adiabatic compression from air remaining inside the ram. After renewing the packing, first operate the ram at low-pressure, low speed to sufficiently bleed the air.|
|1||Piston rod oil leakage||Rod packing (Buffer ring, U-ring)||Packing rubber is perished. Lip is deficient all around.||The packing life or hydraulic oil deterioration and high temperature are possible reasons. 1 Renew hydraulic oil. 2. Check the hydraulic oil temperature. (Below 80 °C is advisable). 3 Check if high temperature locally. Renew. It is possible that abnormally high pressure is working on the packing. 1 Check the operation pressure, cushion pressure. 2Part which is attached to the buffer ring may be abnormal. Inspect the buffer ring.|
|Back up ring||The protrusion of the heel of the packing is excessive.||As a rule, renew the rod packing at the same time. (It is desirable to renew parts which are attached to the buffer ring at the same time). It is possible that abnormally high pressure is the cause. Check the same as above (heel of packing protruding).|
|Wiper ring||Foreign matter is biting into the lip. The lip is damaged. There is also other abnormal damage.||Remove the foreign matter. Renew.|
|Bushing||Wear is excessive and the clearance with piston rod exceeds the maximum permissible value. (Refer to Maintenance Specifications for maximum permissible value.) Large scratch on the sliding part.||Renew. Renew. Also inspect the piston rod.|
|Cylinder head||Scratches, rust on the seal attachment parts.||Remove scratch, rust with oil stone. If it cannot be repaired, renew the cylinder head.|
|‘O’-ring||Foreign matter on inner and outer diameters. O-ring damaged.||• Remove foreign matter. • Renew ‘O’-ring if damaged. • Inspect inside tube: if any scratches or rust, make surface smooth with oil stone. • Inspect cylinder head ‘O’-ring groove: if any scratches or rust, make surface smooth with oil stone. • Inspect back up ring: if any deformation or protrusion, renew. Confirm the above and renew ‘O’-ring.|
|Back up ring||Deformation, protrusion||• Renew, with the ‘O’-ring.|
|2||Oil leakage from cylinder head joint||Cylinder head||Looseness||• Dismantle cylinder head and inspect ‘O’-ring and back up ring. • Check tube and cylinder head thread for damage. If any damage, renew. • After inspection, tighten to specified torque.|
|Bolt||Looseness, stretching, broken||Renew all bolts and tighten to specified torque.|
|Cylinder tube||Abnormal bulge||Replace with new parts. Oil leakage from connecting parts may be caused by abnormal pressure (including cushion pressure). Inspect the tube for bulges, deformation and check the circuit pressure.|
|3||Oil leakage from pipe and cylinder tube welded seam||Cylinder tube pipe (hollow piston rod)||Crack in welding||Replace with new parts. • Cracks will develop into fractures. Fractures are very dangerous, so if any cracks are found, stop work immediately and renew the parts. • Welding on top of cracks will have no effect.|
|4||4-3||Air||Air remaining inside ram. Operation is unsteady||• Bleed the air. For rams that do not have an air bleeder, operate back and forth several times at low pressure and low speed to bleed the air. For rams with an air bleeder, remove the load to reduce the pressure then loosen the air bleeder and completely bleed the air. Note: The ram may expand if it is stopped suddenly. This is due to the compression of the hydraulic oil. This occurs especially with long stroke rams.|
|4-4 Heavy shock loading when changing from extension to retraction and back||Pin bushing/pin||Gap between mounting and pin bushing is too large.||Measure the pin and pin bushing and renew parts if measurements exceed the specifications.|
|4-5 Noisy operation||Oil supply Pin bushing/pin||Insufficient oil. Scuffing at connecting part.||• Add oil. • Replace with new part and add oil.|
|Note: If left in the state where operation is poor, the ram will no longer move and other parts will be affected adversely. Inspect early and carry out appropriate measures.|