Case Magnum 7210, Сервисный бюллетень

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Service Bulletin NTR SB 026 96
Magnum Hitch Diagnostic Codes and Service Manual update
Page 16 of 26
HITCH DIAGNOSTICS BY PROBLEM
8. Hitch raises slowly
A. 1st remote valve is causing PFC pump to operate at high pressure stand by or is using all
the PFC pumps hydraulic flow. Remember the 1st remote has priority over hitch and
remotes valve 2 though 4.
1. See Service Bulletin NTR SB 022 96 using and understanding the 1st remote valve.
2. Operate equipment with 2nd remote valve.
3. Remove restriction from implement hydraulic supply line or valve.
4. Use tractor’s remote valve flow control to control flow to implement valve.
9. Hitch leaks down (engine off)
A.
B.
Isolate the hitch lift assist cylinders from the main rock shaft cylinder to determine if the lift
assist cylinder is leaking.
1. Lower hitch and cap off lift assist cylinder supply line.
2. Place load (weight) on the hitch and raise hitch. Turn tractor engine off.
If hitch does not leak down the problem is with the assist cylinder.
If hitch leaks still leaks down go to step B.
Testing the hitch rockshaft cylinder and the cushion relief valve.
1.
2.
3.
4.
5.
Lower the hitch completely.
Disconnect the hitch supply line to the rockshaft at the hitch valve.
Connect the hitch rockshaft cylinder supply line to remote valve “B” port.
Cap the hitch valve supply port.
Start the engine and use the remote valve to raise the hitch with sufficient weight to cause
leak down.
6. Put remote valve in neutral and close the shut off valve.
to remote valve
If the hitch leaks down the problem is in the rock shaft cylinder area.
A.
B.
C.
Check cushion relief valve per the service manual section 8010 page 10 step 17.
Cylinder piston seal leaking. Order seal kit 230318A1 per service bulletin NTR SB
077 96 issued March 25 1996. DO NOT INSTALL SEAL BACKWARDS see bulletin
for installation information.
Seal ring P.N. 1957863C1 between hitch cover and cylinder crushed or fell out
during assembly.
Make sure seal does not fall out during installation of
cylinder to cover.
If the hitch does not leak down the problem is with the hitch valve.
A. Hitch valve lock check poppet or o-ring is leaking.
B. Hitch valve lock out spool is scored/sticking.