PRIORITY - NOTICEABLE DRIFT OF THE REAR STEERING WHEN USED IN TWO WHEEL STEER MODE ON CERTAIN 438B TAWS BACKHOE LOADERS - COS A LETTER NO. 1 - PI3742 - MAILED COSA Caterpillar

HEBE1427
JANUARY 26, 1995
COSA LETTER No. 1
************ NOTICEABLE DRIFT OF THE REAR STEERING WHEN
* PRIORITY * USED IN TWO WHEEL STEER MODE ON CERTAIN 438B
************ TAWS BACKHOE LOADERS
4307   PI3742
NOTE: This Program must be administered as soon as
possible. When reporting the repair, use "PI3742"
as the Part Number, and "7751" as the Group Number
Causing Failure. If the repair is done before
failure, use "56" as the Warranty Claim
Description Code, and after failure use "96".
COMPLETION DATE  

July 31, 1995  January 31, 1996

There may be noticeable drift in the rear steering of certain
438B TAWS Backhoe Loaders, when used in two wheel steer mode.

Model Identification Number
438B 3KK628, 630, 711, 804, 823, 831, 850, 853, 856, 859,
862, 865, 868, 871, 874, 877, 880, 883, 886, 889,
892-893, 896, 901, 903, 906, 910, 913, 916, 919,
923, 925, 929, 931, 935, 937, 941, 943, 945, 947,
951, 956, 960-961, 965, 968-969, 972, 975, 978, 981,
984, 986, 988, 991, 993, 996, 998, 1002, 1021, 1029,
1030, 1032, 1034, 1036, 1038, 1040-1041, 1043, 1046-
1047, 1050, 1054-1062, 1068-1069, 1075, 1078, 1081,
1083-1088, 1091, 1093, 1096, 1099, 1102-1103, 1108-
1109, 1111, 1115, 1118, 1131, 1134-1135, 1137, 1140,
1142-1146, 1148, 1150, 1152, 1154, 1156, 1158, 1161,
Model Identification Number (continued)
438B 3KK1162-1163, 1165-1166, 1169, 1172-1173, 1177, 1180,
1182, 1184, 1186, 1188, 1190, 1192, 1194-1195, 1198,
1200-1201, 1203-1209, 1212, 1214, 1216, 1218-1219,
1221-1224, 1226-1227, 1229-1231, 1238, 1243, 1245,
1248-1249, 1252, 1254, 1256, 1258, 1260, 1263-1269,
1271, 1273, 1275, 1277, 1284, 1287, 1291, 1295,
1304-1305, 1307, 1309, 1312-1314, 1317, 1326, 1332,
1339, 1341-1342, 1345-1348, 1350-1352, 1355-1356,
1359-1360, 1363-1364, 1367, 1370, 1376-1377, 1383-
1384, 1386, 1388-1389, 1391, 1396-1397, 1400, 1407,
1409-1410, 1412, 1414-1415, 1421-1422, 1429-1430,
1434, 1437-1438, 1440, 1446-1447, 1449, 1460-1461,
1465-1466, 1470-1471, 1475-1477, 1480-1483, 1487,
1491-1492, 1496-1497, 1501-1502, 1513-1514, 1533,
1541, 1552-1553, 1557-1561, 1569-1570, 1575-1576,
1581-1583, 1586-1587, 1589-1590, 1593, 1596, 1603-
1604, 1612-1613

1 - 3J1907 Seal - O-Ring
4 - 3K0360 Seal - O-Ring
2 - 8T4121 Washer
2 - 8T6466 Bolt
1 - 1V9633 Diode As
9 - 6V8397 Seal - O-Ring
3 - 6V8398 Seal - O-Ring
1 - 6V8936 Reducer As
1 - 6V9829 Cap As
1 - 6V9837 Tee - Swivel
1 - 1125972 Hose As
1 - 1212809 Hose As
1 - 1228301 Valve Group
1 - 1228886 Bracket
1 - 1230268 Harness As

Remove lock valve from the machine and replace with a modified
one using a new bracket. Reconnect using a new hose and
connector, harness assembly, and diode assembly.
See attached Rework Procedure.

AVSpare Dealer Suggested Customer Suggested
Parts Labor Hrs Parts Labor Hrs Parts Labor Hrs
(D/N) (Sell)  (C/L) (Sell)
100% 4 0 0 0  0

Handle the parts in accordance with your Warranty Bulletin on
warranty parts handling.
MAKE EVERY EFFORT TO COMPLETE THIS PROGRAM AS SOON AS POSSIBLE.
Attachment
1-Rework Procedure

Rework Procedure to Install 1228301 AWS Lock Valve
Disassembly of the current machine
1. Disconnect the seat from the cab floor.
2. Remove rear cab floor plate.
3. Disconnect and discard the 1125971 Hose Assembly from elbow
on the rear of 1034921 AWS Valve and elbow on the right hand
side of 1177076 Lock Valve.
4. Cap elbow on the rear of the 1034921 AWS Valve using a
6V9829 Cap and a 6V8397 Seal.
5. Disconnect the 1125971 and 1079431 Hose Assemblies at rear
of 1177076 Lock Valve.
6. Disconnect and discard the 1125972 Hose Assembly from the
front of 1177076 Lock Valve and elbow on left hand steer
cylinder port. Remove the seal from the elbow in the steer
cylinder port.
7. Disconnect the 1060909 Hose Assembly from the front of
1177076 Lock Valve.
8. Remove and retain 4 - 6V8634 Connectors and 1 - 6V8724 Elbow
from the 1177076 Lock Valve. Remove and discard all seals,
but retain the connectors and elbow.
9. Remove and discard the 1177076 Lock Valve and the 1126081
Plate Assembly.
NOTE: 1126081 Plate Assembly was produced in two
versions, with either open ended slots for axle
mounting or with holes. Plates with slots are
simple to remove once the axle bolts have been
loosened. Plates with holes were fitted to a few
early machines and are more difficult to remove as
the bolts cannot be taken completely out of the
axle while it is still attached to the frame.
Assembly of the new Valve
1. Install the 1228886 Bracket to the axle using the existing
axle bolts.
2. Install the 6V8724 Elbow (retained during disassembly) to
1228301 Lock Valve Assembly Port marked 'T' using a 3J1907
Seal and orient the elbow to point downward. Do not tighten
the locknut.
3. Install 4 - 6V8634 Connectors (retained during disassembly)
into 1228301 Lock Valve in ports labelled V1, V2, R1, R2
using 4 - 3K0360.
4. Install 1228301 Lock Valve onto the 1228886 Bracket using
2 - 8T6466 Bolts and 2 - 8T4121 Washers. Install valve with
ports marked R1 and R2 towards front of machine.
5. Install new 1125972 Hose Assembly between 1228301 Lock Valve
Port marked 'R2' and left hand steer port elbow using
2 - 6V8397 Seals. Connect 90 degree hose end to lock valve
connector and orient horizontally.
6. Reconnect 1060909 Hose Assembly to 1228301 Lock Valve Port
marked 'R1' using a 6V8397 Seal and orient the hose end
horizontally.
7. Install the 90 degree end of the 1212809 Hose Assembly to
the 6V8724 Elbow in port marked 'T' on the rear face of
1228301 Lock Valve using a 6V8397 Seal. Route the hose under
left hand edge of lock valve and tighten locknut on elbow.
8. Disconnect the 8Y8608 Hose Assembly (return from HMU to
tank) from the reducer on the tee at the front tank side of
the hydraulic filter. Remove seal from reducer. Install a
6V9837 Tee between reducer and 8Y8608 Hose Assembly using a
6V8398 Seal. Orient the middle port of tee to point
horizontally rearward and connect the 8Y8608 Hose Assembly
using a new 6V8398 Seal.
9. Install a 6V8936 Reducer onto the horizontal port of the
6V9837 Tee using a 6V8398 Seal. Connect the 1212809 Hose
Assembly to the reducer using a 6V8397 Seal.
10. Reconnect 1079431 Hose Assembly to port marked 'V1' on rear
of 1228301 Lock Valve using a 6V8397 Seal.
11. Reconnect 1125971 Hose Assembly to port marked 'V2' on rear
of 1228301 Lock Valve using a 6V8397 Seal.
12. a. Disconnect 1047054 Harness from 1047051 harness at
connectors at the base of loader control lever.
b. Install 1230268 Hardness Assembly into 1047051 Harness
connections using a 6-pin male and female connectors.
c. Install 1V9633 Diode into 1230268 Harness at 4 pin
connector.
d. Disconnect 1047054 Harness from circle steer (top)
solenoid on 1034921 AWS Valve.
e. Connect male and female 2 pin connectors of 1230268
Harness to above connectors.
f. Connect remaining 2 pin connectors of 1230268 Harness
to connector on solenoid of 1228301 Lock Valve.
g. Tie wrap harness as required to the underside of the
cab to secure and keep away from the axle.
13. Start machine and check for leaks by operating each steering
mode of AWS.
14. Engage AWS mode and operate system from lock to lock a
number of times to ensure all air is purged from the system.
15. Reassemble cab floor plate and seat.
16. Affix a warning decal to the center of the vandal proof
cover. The decal part numbers are:
1246290 English
1246291 Italian
1246293 French
1246294 German
1246295 Portuguese
1246296 Spanish
1246297 Danish
NOTE: A supply of decals will be sent from AVSpare
U.K., along with a Supplement to add to the
Operation and Maintenance Manual of each machine.