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Trouble Shooting

In addition to the various components of the Range Shift Air System, the Splitter Shift Air System utilizes a splitter cylinder and a separate lever-mounted Split- ter Selector Valve OR the Roadranger Control Valve A- 4900. See Air System Schematics.

CONSTANT AIR from the air filter/regulator assem- bly is supplied to the splitter cylinder at the port on right side of cylinder cover. The Insert valve installed in cover (see Page 37) provides the proper air flow needed to move the splitter piston in the cylinder (rearward to engage splitter gearing; forward to dis- engage splitter gearing).

WHILE IN HIGH RANGE ONLY, AIR needed to make the splitter selection and complete the shift is supplied to the control valve from tee fitting at the High Range or “H” Port of slave valve. When the splitter selection is made, the AIR passes through the control valve and is supplied to the Center Port of cylinder cover.

With Splitter Control Button in the “DIR.”/ REARWARD position, the “D” or “SP” Port of control valve is CLOSED and NO AIR is supplied to the Cen- ter Port of Splitter cylinder cover.

If the transmission fails to shift or shifts too slowly to or from the “split” position, the fault may be in the Splitter Shift Air System or related components of the Range Shift Air System.

To locate the trouble, the following checks should be made with normal vehicle air pressure supplied to the system, but with the engine off. See CAUTION, Page 25. NOTE: It is assumed that correct PSI readings were

obtained from the air filter/regulator and ail air lines have been checked for leaks.

1. Air Supply (See Air System Schematics.) With the gear shift lever in neutral, select HIGH RANGE and loosen the connection at the “S” Port of Splitter Selector Valve or “H” Port of Mas- ter Control Valve until it can be determined that AIR is supplied to valve. Reconnect air line.

If there is NO AIR, check for a restriction in the 1/8" O.D. air line between the control valve and

slave valve, making sure this line is connected to tee fitting at the High Range or “H” Port of slave valve.

Button in “DIR.” (“D” Port CLOSED)


WHILE IN HIGH RANGE, the button can be moved FORWARD to operate in UNDERDRIVE or OVER- DRIVE. The “D” or “SP” Port of valve is OPENED when splitter selection is made, supplying AIR to the Center Port of Splitter cylinder cover.

B u (“D” Port OPENED) t t o n i n U . D . o r O . D .


(“SP” Port OPENED)

NOTE: WHILE IN LOW RANGE, the mechanical in- terlock of Master Valve prevents movement of Splitter Control Button to the FORWARD po- sition.

  • 2.

    Selector or Roadranger Valve (See Pages 38-39 and Air System Schematics.) With the gear shift lever in neutral, disconnect the 1/8” O.D. air line at the Center Port of splitter cylinder cover, making sure this line leads from the “D” Port of Splitter Selector Valve or “SP” Port of Master Valve.

    • A.

      WHILE IN HIGH RANGE, move the Splitter Control Button FORWARD. There should be AIR flowing from disconnected line. Move the button REARWARD to shut off air flow and re- connect air line.

    • B.

      If the preceding conditions did not exist, the control valve is defective, or there is a restric- tion in the air lines.

  • 3.

    Splitter Cylinder. (Refer to the following illustra- tion.)

If any of the seals in the splitter cylinder as- sembly are defective, the splitter shift will be af- fected. The degree of air lost will govern the degree of failure, from slow shifting to complete shift failure. A. Leak at O-ring A results in a slow shift to

engage splitter gearing; pressurizing of trans- mission case; splitter gearing can be dis- engaged.

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