jcb JS200 Service Manual page 461

Sectyion F
5 - 5
Fault Finding (continued)
2-Speed Control Function
Fault
1. Travel is not linear
2.Will not go into 2nd.
3.Will not go into 1st.
9803/6400
Transmission
Motor/Gearbox
Possible cause
1. Plunger is not switched
1) Foreign matter is caught between
plunger and body.
* 2) Spring is not assembled correctly.
3) Spring is broken.
*
4) Foreign matter is trapped in spool
galleries.
2. Pressurised oil leaks due to abnormal
wear of 2-speed control piston
3. 2-speed control piston is not assembled
correctly
4. Steel ball is abnormally worn.
5. Set pressure is rising due to
abnormal wear of spools.
6. The orifice of the 2-speed piston cavity
drain is incorrect.
7. The orifice of the 2-speed piston cavity
drain is clogged.
8. Number of washers is different and set
pressure is different on the left and right.
1. Plunger is not switched
1) Foreign matter is caught between
plunger and body.
*
2) Foreign matter is trapped in spool
galleries.
2. Pressurised oil leaks due to abnormal
wear of 2-speed control piston.
3. 2-speed control piston is not assembled
correctly.
4. The orifice of the 2-speed piston cavity
drain is clogged.
1. Spring is not assembled correctly.
2. Spring is broken.
3. Set pressure is rising due to abnormal
wear of spools.
Countermeasure or remedy
Completely remove foreign matter, repair
the damage and reassemble after cleaning.
Replace if damage or leakage is excessive.
Assemble spring in specified position.
Renew spring.
*
Completely remove foreign matter, repair
the damage and reassemble after cleaning.
Replace if damage or leakage is large.
Replace the 2-speed control piston.
Completely remove foreign matter and
reassemble after cleaning.
Assemble 2-speed control piston to the
specified position.
Replace steel balls. Completely remove
foreign matter and reassemble after cleaning.
Replace spool. Completely remove
foreign matter and reassemble after cleaning.
Confirm orifice diameter.
Reassemble after cleaning.
Reassemble using correct number of washers.
Completely remove foreign matter, repair the
damage and reassemble after cleaning.
Replace if damage or leakage is excessive.
Completely remove foreign matter, repair
the damage and reassemble after cleaning.
Replace if damage or leakage is excessive.
Replace the 2-speed control piston.
Completely remove foreign matter and
reassemble after cleaning.
Assemble 2-speed control piston to the
specified position.
Reassemble after cleaning.
Assemble spring to specified position.
Replace spring. Completely remove foreign
matter, repair the damage and reassemble after
cleaning. Replace if the damage or leakage
is excessive.
Replace spool. Completely remove
foreign matter, repair the damage and
reassemble after cleaning. Replace if the
damage or leakage is excessive.
Section F
5 - 5
Issue 2*