Usage:
3T9365;
D6D ( 37C, 74W, 3X, 19X, 30X, 32X, 3T8204;
36C, 75W, 4X, 6X, 20X, 31X, 33X) 3T8203
Reference: Service Manual, Parts Book
This instruction gives the procedure to install and adjust these steering and brake control valves to get smooth steering clutch and brake modulation on the above machines. Adjustments can be made to the steering and brake control valve so it will give smooth modulation. Use this instruction, along with the Service Manual and Parts Book, for the correct installation and adjustment procedures.
NOTE: Some additional 7G4241 and 7G6005 Shims may be needed to make adjustments to the steering clutch and brake valves. Get these shims from the Parts Department before adjustment of the valve.
NOTE: 3T8203 and 3T8204 Valve Groups must be equipped with certain springs before the pressure adjustments can be made. See page 11 for the correct locations, part numbers and descriptions for the springs.
1 If adjustments are to be made to a valve mounted on the tractor, do not remove the valve. Be sure that housing (2) does not touch cover plate (3). Housing (2) must be 0.25 ± 0.13 mm (.010" ± .005") above plate (3). If a new steering and brake control valve is to be installed, remove steering control valve (1) from the machine. Thoroughly clean plate (3) under the steering valve. Install new seals in the plate, and install the new steering clutch hydraulic control valve (see page 1 for the part number) where the former control valve was removed. Be sure housing (2) is above the machined mounting surface for the control valve; see the dimensions above. Tighten the four bolts that hold the valve body to a torque of 45 ± 7 N·m (32 ± 5 lb-ft). Install elbows (4) after the four bolts have been tightened.
2 Adjust the steering clutch control linkage to the specifications shown in the Service Manual. Adjust length (B) of rod (5) to 555.0 mm (21.85").
3 Install 0-4150 kPa (0-600 psi) pressure gauges at locations (X) to check the steering clutch pressure, and at locations (Y) to check the brake pressure. Operate the machine to warm the transmission oil to the normal temperature for operation. With the steering clutch control lever held in the maximum travel position, the brake pressure must be as shown in the chart above. Be sure the engine R/Min (RPM) is adjusted to the correct specification.
4 Put a mark on steering clutch control lever (6) at the edge of the dash group at location (W). Pull the lever out to the limit of its travel, and put a mark on the lever at the edge of the dash at (V). Put four marks (R), (S), (T) and (U) on the lever at the locations shown.
5 With the engine at high idle, pull control lever (6) out until each mark is even with the dash. Make a record of the steering clutch and brake pressures at each mark. NOTE: The parking brake or foot brake pedal must not be applied during the pressure test. Measure the distance between marks (V) and (W).
6 If the measurement between marks (V) and (W) is not 177.8 mm (7.0"), the formula that follows must be used to figure the correct ratio between the actual rod travel and the dimensions on the chart. This ratio will be the pressure chart displacement.
Example: If the total rod travel is 190.5 mm (7.5") [dimension (V) to (W)] and the steering clutch pressure is taken at 57.0 mm (2.25") mark (S), find the correct pressure chart displacement as follows:
7 If needed, use this formula to determine the correct pressure chart displacement for each reading at (R), (S), (T) and (U). The pressure reading can be used without any conversion. Use the correct chart, for your machine (pages 7 and 8), and mark the two points for steering clutch pressure modulation in section (A) and brake pressure in section (B).
8 Draw a straight line between the two location points in each pressure zone on the chart. If the line stays within tolerance zones (C) for the steering clutch and (D) for the brake for each system pressure, no modifications are needed to the steering and brake control valve. If the pressures are not within specification see page 9 for the adjustment procedure.
Valve Adjustment Procedure
1 All valve adjustments can be made if plugs (1) (left side) and (2) (right side) are removed from the steering and brake control valve. Be sure the engine is stopped and the pressure reading on the gauges is at zero before removing plugs (1) and (2). Slowly remove plugs (1) or (2), 7G4241 Shims (3) and return spring (4). Each shim (3) will change the steering clutch pressure the following amount: D5B - 75 kPa (11 psi); D6D - 54 kPa (8 psi). Each shim (3) will change the brake pressure the following amount: D5B - 65 kPa (9 psi); D6D - 47 kPa (7 psi).
2 To adjust the steering clutch modulation pressure within the tolerance zone, add 7G4271 Shims (3) to reduce the pressure, or remove shim (3) to increase the pressure. Do not use more than thirteen shims (3) for each valve spool.
3 Brake pressure can be adjusted a small amount with 7G6005 Shims (5). These shims will change the pressure per shim as follows: D5B - 12 kPa (2 psi); D6D - 4 kPa (0.6 psi). Add shims to increase pressure or remove shims to decrease the brake pressure. This pressure adjustment will not change steering clutch pressure. Do not use more than 26 of the 7G6005 Shims for each valve spool. One 7G6005 Shim must be used to provide centering for the outer valve spring. Both ends of the outer spring must be manually put in the center position on the valve before installation of the valve into the valve housing.
Spring Description
1 3T8203 and 3T8204 Control Valve groups must be equipped with the springs that follow: 6T7221 Return Spring (1), 3T9366 Outer Spring (2) and 6T7222 Inner Spring (3). See the chart below for the description of the springs. Install these new springs if necessary.
