CX31 and CX31 HT On-Highway Transmissions Caterpillar

The CX31 nomenclature covers a broad range of transmission products with the same clutch sizes. As a result, using the correct CX31 arrangement numbers is important for the owners, users, and service personnel. There are three CX31 transmissions used in the Cat truck. The serial number prefixes D9F and HTC are used for the non-retarder CX31 transmission. The serial number prefix D9R is used for a CX31 transmission equipped with a retarder. The three transmissions can be ordered with different options. The options include a torque converter, rear PTO and yokes. The Cat dealer will need the prefix and all of the serial numbers to identify a particular transmission properly.

For a quick reference, record the serial numbers by writing the serial numbers in the space that is provided below the illustration.

Product Identification

Illustration 1	g02446877

Transmission Serial Number____________________

Torque converter Serial Number____________________

Serial Number Plate (SN)

Illustration 2	g02445476

Model Views

Illustration 3	g03443745
(1) Filter outlet pressure coupler (2) Filter inlet pressure coupler (SOS) (3) Two M16x2 rear mounting and lifting points (lifting points can also provide vehicle support) (4) Conventional ten bolt PTO at 1:00 o'clock position (5) No. 1 SAE J615 side mounting bolt pad spacing six M16 x 2 threads (6) Oil filler (7) Standard sump/oil pan shown 120 mm (4.72 inch) deep. Not displayed shallow sump 80 mm (3.2 inch) deep. Not displayed retarder sump 142 mm (5.6 inch) deep. (8) Four M16x2 threaded mounts (9) Transmission output speed sensor (10) Option 1085 N·m (800 lb ft) rear PTO capability. Specifications in PTO section (11) Rear magnetic drain plug (SAE J1926 #12 port) (12) SAE J1926 #4 auxiliary PTO lube port (13) Output yoke (two options) (14) Transmission mounted cartridge type oil filter (15) Lift bracket

Illustration 4	g03444076
(16) Lift bracket (17) No. 1 SAE J617 flywheel housing for 12 and 24 bolt mounts (18) Engine output speed sensor (19) Transmission breather/filter (20) OEM electrical interface for 24 and 70 pin connectors (21) Electronic Control Unit (ECU) (22) Torque converter output speed sensor (23) Transmission oil temperature sensor (24) Oil level sensor (25) Solenoid protective shield (26) SAE J1926 #4 auxiliary PTO lube at clutch pressure port (27) Conventional ten bolt PTO at 8:00 o'clock position (28) SAE J1926 #16 inlet from cooler port (29) SAE J1926 #16 outlet to cooler port (30) Transmission main relief valve (31) Drain plug SAE J1926 #16 (1 5/16-12 O-ring face seal)

Illustration 5	g03445617
(32) Lockup clutch pressure coupler (33) Clutch #1 (C1) pressure coupler (34) C2 pressure coupler (35) C3 pressure coupler (36) C4 pressure coupler (37) C5 pressure coupler (38) Six base supports (39) Three M8x1 bolts (40) Magnetic filter (access cover) (41) Lube pressure coupler (42) Sump heater SAE J1928 #16 port (43) Converter outlet temperature sensor

Lifting

• There are two acceptable lifting methods for the CX31 transmission. Option A utilizes Columbus McKinnon hoist rings at the two side transmission mounting pads and the two rear transmission mounting holes. Option B utilizes 1/2" J-hooks in the designated holes on the two lifting brackets (one on each side). There are lift films on the bracket to indicate which hole to use on the right side bracket. Also note that only Option A or Option B can be used, but no combination of the two. The transmission is designed to sit level on the transmission's six base supports as shown in Illustration 6.

• Care must be taken when lifting to avoid damaging the following components that are mounted externally on the transmission: ECM, ECPC valves, solenoids, wire harness and sensors.

Altitude Restrictions

Note: There are no restrictions based on altitude.

Illustration 6	g03445749
Lifting points

Illustration 7	g03445819
(44) Retarders will add 104 mm (4.09 inch) to the length of the CX31. (45) Retarder activation solenoid (46) Retarder activation pressure coupler (47) SAE J1926 #24 inlet from cooler port (48) SAE J1926 #24 outlet to cooler port (49) Identification and serial plate

Illustration 8	g03476261
CX31 with retarder (bottom view) (50) Retarder inlet pressure coupler (retarder valve) (51) Lubrication pressure coupler (retarder valve) (52) Torque converter outlet pressure coupler (retarder valve) (53) Retarder outlet pressure coupler (retarder valve)

Note: Caterpillar transmissions are manufactured, assembled, and tested by using hydraulic diagnostic couplers. These quick disconnect couplers for checking system pressures remain on the transmission for the convenience of the owners and service personnel. Unless otherwise stated, all quick disconnect couplers conform to SAE-J1502 standards.