NEHT6001-04February 1998

TESTPROCEDURE

785, 789, 784B, 785B, and 789B TruckTransmission 3T-0030 and 3T-0034 Arrangements

Safety

Improper operation, lubrication, maintenance, or repair of this product can bedangerous and could result in injury or death. Do not operate or perform anylubrication, maintenance, or repair on this product until you have read andunderstood the operation, lubrication, maintenance, and repair information.

Hot oil and components can cause personal injury. Do not allow hot oil orcomponents to contact skin.

Always use a board or cardboard when checking for a leak. Escaping fluidunder pressure, even a pin-hole size leak, can penetrate body tissue, causingserious injury and possibly death. If fluid is injected into the skin, it must besurgically removed within a few hours by a doctor familiar with this type of injury.

NOTICE

Operations that may cause product damage are identified by notice labels in thispublication.

2

Truck Transmission Installation ProcedureArrangement # 3T-0030 and 3T-0034

Figure 1

When using the large drive shaft, install drive adapter (A, Figure 2) onto the inputyoke of the transmission. Now slide adapter (B, Figures 2 and 3) onto adapter(A), and tighten the setscrew. Install adapter (C) onto the input drive shaft of thetest bench. Install and align the transmission with the input drive shaft of the testbench.

Slide adapter (C, Figure 3) over adapters (A and B). Tighten the setscrew onadapter (C). Install the drive shaft guard.

NOTEIf the small drive shaft is used, only adapters (A and B)are needed.

3

Figure 2

Figure 3(1) Lube pressure 2. (2) Lube pressure 1.

J 1

2

A

B C

4

Figure 4

NOTEReview Special Instruction SEHS8763 for spindleoperation, if required.

Remove the collet (shown in SEHS8763) and drawbar bolt from spindle (F, Figure4). Make sure the O.D. of spline adapter (E), the o-ring, and the bore of spindle(F) are lubricated. Insert adapter (E) into spindle (F) (this is a close sliding fit).Align the hole in the end plate of spline adapter (E) with the pin inside of spindle(F). Install the drawbar bolt. Turn the drawbar bolt (CW) to pull adapter (E) intothe spindle bore past the o-ring until it bottoms out. Tighten the drawbar bolt to170 N⋅m (125 ft lb).

NOTEThe o-ring on the O.D. of spline adapter (E) will centerthe adapter within the spindle bore.

5

Figure 5

Install adapter (D, Figure 5) onto the transmission case. Install bolts (D3) in thetwo bottom holes. Install bolts (D5) and link bracket (G2) in the top two holes.Slide spindle (F) with spline adapter (E) onto the transmission output shaft. Alignthe spindle pilot with the bore in plate (D) on transmission, and bolt the spindleinto place. Aligning the spindle will require lifting the spindle during installationto raise the shaft to a center position.

D

E

D5 G2

D3

BB

F

AA

6

Figure 6

NOTERefer to Special Instruction SEHS8763 for additionalinformation on operation of spindle (F).

After the spindle has been installed, loosen lock bolt (AA, Figure 5), and adjustthe spindle inward with hex nut (BB) until the spline adapter contacts the carrierand stops. Then back the spindle out to provide a 3 to 4 mm (.12 to .16 in) gapbetween the carrier and the spline adapter. This gap can be measured with asuitable shim through the access hole in adapter plate (D). Lock the spindle inplace with lock bolt (AA) after setting the gap.

Connect lube line (3, Figure 6) from the test center to the spindle lube inlet.Maintain an oil pressure of 69 kPa (10 psi).

Secure the transmission to the test center using link brackets (G2), ratchetingturnbuckle (G1), and chains to prevent transmission movement during testing.Tighten all bolts to their proper torque setting.

S

F

G2

G1

3

7

Figure 7

Remove filter housing from the side of transmission and drain plug from thebottom, and allow the oil to drain during testing.

NOTICE

Do not remove the drain plug which drains the rear cavity of transmission. Thisplug must be in place to provide an adequate level of oil for lubrication.

8

Figure 8(4) Upshift solenoid. (5) Downshift solenoid. (6) Lock-up clutch solenoid.

(7) Pump pressure and adapter (O). (8) Input flow for oil supply to transmission and adapter (L). (9) Lube outlet and adapter (K). (10) Lock-up pressure and adapter (P).

(Q3). 1U-9482 Test Cable (transmision switch connector). (Q4) 4C-5974 Cable Adapter.

Q4

4

K

7

56

9

10

8

Q3

L

O

9

Figure 9

10

Figure 10

Install adapter (L, Figure 8) onto the lube outlet. Connect a hose from adapter(L) to the inlet of one of the flowmeters. Install adapter (K), and connect a hosefor oil supply to the transmission controls from the test bench. Install adapter (O)and pressure gauge to measure pump pressure. Install adapter (P) andpressure gauge to measure lock-up clutch signal pressure.

Install adapter (I, Figure 9) onto the lube inlet. [Some transmissions may requirean additional adapter (J) to be used between the gear case and adapter (I)].Connect a hose from adapter (I) to the outlet of the same flowmeter used foradapter (L). Connect an 8T-0853 Gauge onto adapter (I) to measure lubepressure.

Remove the transmission cover and the pilot oil plug from the valve group. Installadapter (M, Figure 10) and connector to measure pilot pressure. Install test cover(H) and bolts to hold it in place. Install connectors (R) at locations (A, B, C, D, E,F, and G) to measure clutch pressures. Pressure tap (H1) is not used.

NOTEFigure 10 shows the transmission hooked up to a VMSMonitor. If this monitor is not available, use 8T-0854Gauges in place of the connectors.

M 12

B

C

D

E

F

H

H1

R

G

A

11

Figure 11

Use the 9U-7500 Shift Analyzer Group (Q, Figure 11) to shift the transmission.Connect the shift analyzer to the transmission using the 1U-7498 Extension Cableand 1U-9482 Test Cable with 4C-5974 Cable Adapters. Make sure theappropriate plug assemblies (Q3) on the test cable are connected to thefollowing: upshift solenoid (4, Figure 8), downshift solenoid (5), lock-up clutchsolenoid (6), and transmission switch (11).

Connect the Transmission Analyzer II to power source and use the operatinginstructions with the unit, if necessary.

12

Parts Needed For Testing 785 and 789 Truck Transmission

Figure 12

REF QTY PART # DESCRIPTION FUNCTION

A 1 1 1U-8847 Drive Adapter Connects to transmission2 4 2H-3740 Bolts 3/4-16 x 1.25" input yoke3 1 1U-5936 Drive Adapter (Not Shown) Connects to transmission

3T-0030 Ar. Input Yoke

B 1 1 1U-9131 Drive Adapter Adapts test bench driveshaft to input driveadapter (A).

C 1 1 1U-9359 Test Bench Adapter Adapts test bench driveshaft to input drive adapter (A). Only required for largedriveshafts.

DC POWER AC POWER

®

9U7499TRANSMISSION

ANALYZER II

A B C Q E F

JD

G

H

K

MO

P

L

I

13

REF QTY PART # DESCRIPTION FUNCTION

D 1 1 1U-5935 Plate Assembly Adapts spindle to2 2 2J-3506 Nut 3/4-10 transmission.3 2 0L-1178 Bolt 3/4-10 x 2"4 2 5P-8248 Washer 3/45 2 1B-4367 Bolt 5/8-11 x 3.5" 6 2 4B-5275 Washer 5/8 7 2 1D-4720 Nut 5/8-11 8 1 5D-6428 O-Ring

E 1 1 1U-8654 Splined Collar Adapts spindle to transmission output shaft.

F 1 1 1U-5999 Spindle Group Supports transmission2 4 8B-7997 Bolts, 1/2-13 x 2" output shaft.

G 1 4 1U-9722 Ratcheting Turnbuckle Secures transmission to2 2 6V-2156 Link Bracket test center.

H 1 1 4C-48981 Test Cover Covers hydrauliccontrols during test.

1 FT-1874 can be used, if available.

I 1 1 1U-8301 XT-3 90 degree Elbow Adapter for oil supply2 1 1U-8298 XT-3 Fitting to transmission.3 2 1P-4578 Split Flange 4 1 8C-9024 Nipple Q.D. 5 4 0T-0319 Bolt 7/16-14 x 2" 6 1 6V-3965 Nipple Q.D.7 1 3J-1907 O-Ring

J 1 1 5T-7967 Adapter Some transmissions may2 4 5F-8807 Bolt 1/2-13 x 1.25" require (J) with adapter (I).

K 1 1 1U-8299 XT-3 Fitting Adapter for lube2 1 1U-8301 XT-3 90 degree Elbow (oil supply). 3 1 6V-3965 Nipple Q.D.4 1 8C-9024 Nipple Q.D. 5 2 1P-4579 Split Flange 6 4 9S-1326 Bolt 1/2-13 x 2.5" 7 1 3J-1907 O-Ring

L 1 1 1U-8299 XT-3 Fitting Adapter for lube2 1 1U-8304 XT-3 90 degree Elbow outlet. 3 1 6V-3965 Nipple Q.D. 4 1 8C-9024 Nipple Q.D. 5 2 1P-4579 Split Flange 6 4 9S-1326 Bolt 1/2-13 x 2.5" 7 1 3J-1907 O-Ring

14

REF QTY PART # DESCRIPTION FUNCTION

M 1 1 3B-6552 Elbow Adapter to measure 2 1 3B-7282 Nipple pilot pressure.3 1 6V-4142 Valve Nipple

O 1 1 6V-3966 Nipple Q.D. Adapter to measure 2 1 3K-0360 O-Ring pump pressure. 3 1 8J-7844 Adapter

P 1 1 6V-3965 Nipple Q.D. Adapter to measure2 1 3J-1907 O-Ring lock-up signal pressure.

Q 1 1 9U-7500 Shift Analyzer Shifts transmission.2 9U-7498 Extension Cable3 1U-9482 Test Cable4 4C-5974 Cable Adapters

R 1 7 8T-0854 Gauge 1000 kPa (145 psi) Connectors to measure 2 7 6V-4144 Q.D. initial pressures (not

shown).

S 1 1 1U-9586 Swivel Head Support Group Supports transmissionon work table (not shown).

T 1 9 8T-0855 Gauge 4000 kPa (0 to 580 psi) Gauges to measure 2 9 6V-4144 Q.D. clutch, pump, pilot,

and lock-up pressures(not shown).

U 1 1 8T-0853 Gauge 400 kPa (0 to 58 psi) Gauge to measure 2 1 6V-4144 Q.D. lube pressure

(not shown).

15

Truck Transmission Test Procedure

Prior to testing, do the following:

a. Warm the oil in the test bench to 50°C (125°F). Adjust the supply oil to57 ± 4 Lpm (15 ± 1 gpm), and maintain this flow and temperature for theduration of the test.

b. Rotate the input shaft counterclockwise (CCW) at 600 ± 5 rpm inNEUTRAL.

c. Shift the transmission through all directions and speed ranges toeliminate air from the transmission controls.

d. Check for lock-up or excessive drag in all ranges.

e. Stop rotation of the input shaft. Use the following procedures to checkthe transmission.

NOTICE

Do not shift the transmission into reverse at any input speed other than 600 rpm.

Priority (pilot) Reducing Valve

1. Adjust input flow to 57 ± 4 Lpm (15 ± 1 gpm).

2. Adjust input rotation to 700 ± 30 rpm in NEUTRAL 2 (N2).

3. Shift the transmission into FIRST (1) range.

4. Check the priority reducing valve pressure. It must be 1725 ± 70 kPa(250 ± 10 psi).

16

Neutralizer Valve

1. Stop input rotation in a range other than NEUTRAL 1 (N1) or NEUTRAL 2(N2). Stop input to transmission.

2. Adjust input flow to 57 ± 4 Lpm (15 ± 1 gpm). Adjust the input shaftrotation to 700 ± 5 rpm.

3. Neutralizer valve must prevent any pressure rise at any of the selectorvalve stations.

4. Shift the transmission into NEUTRAL 1 (N1). Pressure at station (C) mustrise to normal.

Lube Circuit Check

1. Shift to SECOND (2) range. Adjust the input flow to produce a lube flow of152 ± 4 Lpm (40 ± 1 gpm). Adjust the input rotation to1850 ± 30 rpm.

2. Lube 1 pressure must be 57.9 ± 10.3 kPa (8.4 ± 1.5 psi).Lube 2 pressure must be 56.5 ± 10.3 kPa (8.2 ± 1.5 psi).

17

Initial Pressure Check

1. Remove test cover (H). Remove the load piston plugs (12, Figure 10) fromall selector valve stations, except station (D). Reinstall test cover (H).

2. Adjust input rotation to 700 ± 5 rpm. Adjust input flow to 57 ± 4 Lpm(15 ± 1 gpm).

3. Shift the transmission through all ranges, and record the primary clutchpressures in each range.

4. Compare the recorded readings with the following chart.

NOTEUnless otherwise specified all pressures are+50 / -35 kPa (+7 / -5 psi).

GearRange

ClutchesEngaged Pump

Selector Valve Stations - kPa (psi)

A B C D E F G

N1 � 3

2515kPa/min

(365psi/min)

AllRanges

0 0 480(70)

0 0 0 0

N2 1 � 0 475(69)

0 0 0 0 0

R 1 6 0 475(69)

0 0 0 0 428(62)

1 1 5 0 475(69)

0 0 0 448(65)

0

2 2 5 525(76)

0 0 0 0 448(65)

0

3 1 4 0 475(69)

0 0 428(62)

0 0

4 2 4 525(76)

0 0 0 428(62)

0 0

5 1 3 0 475(69)

480(70)

0 0 0 0

6 2 3 525(76)

0 480(70)

0 0 0 0

18

Low Idle Pressure Check

1. Replace load piston plugs (12), removed in the Initial Pressure Check.Replace test cover (H).

2. Adjust input rotation to 700 ± 5 rpm. Adjust input flow to 57 ± 4 Lpm(15 ± 1 gpm).

3. Shift the transmission through ranges N1, N2, R, and 1. Record theprimary clutch pressures in each range.

4. Compare the recorded readings with the following chart.

NOTEUnless otherwise specified, all pressures are +240 /-100 kPa (+35 / -15 psi).

GearRange

ClutchesEngaged Pump

Selector Valve Stations - kPa (psi)

A B C D E F G

N2 1 � 2515kPa/min(365

psi/min)All

Ranges

0 2760(400)

0 0 0 0 0

R 1 6 0 2760(400)

0 0 0 0 2760(400)

1 1 5 0 2760(400)

0 0 0 2760(400)

0

Dual Stage Relief Valve Adjustment

1. Adjust input flow to 57 ± 4 Lpm (15 ± 1 gpm). Adjust input rotation to700 ± 30 rpm with the lock-up solenoid de-energized. Minimum pumppressure should be 2515 kPa (365 psi).

2. Adjust input flow to 150 ± 4 Lpm (39 ± 1 gpm). Adjust input rotation to1850 ± 5 rpm. Pump pressure should be approximately 3070 kPa(445 psi).

3. Energize the lock-up clutch solenoid. Pump pressure must be2100 ± 103 kPa (305 ± 15 psi).

4. If this pump pressure is not correct, adjust the pressure by adding orremoving shims from station (D) in the transmission control (adding shimsmakes the pump pressure decrease, and removing shims makes thepressure increase).

19

5. De-energize the lock-up solenoid. Pump pressure must again beapproximately 3070 kPa (445 psi).

6. Adjust input flow to 57 ± 4 Lpm (15 ± 1 gpm) and input rotation to800 ± 30 rpm. Pump pressure must again drop to approximately2760 kPa (400 psi).

20

High Idle Pressure Check

1. Adjust the input flow to 150 ± 4 Lpm (39 ± 1 gpm). Adjust input rotation to1850 ± 30 rpm.

2. Shift the transmission through all ranges, and record the primary clutchpressures in each range.

3. Compare the recorded readings with the following charts.

NOTEUnless otherwise specified, all pressures are+240 / -100 kPa (+35 / -15 psi).

GearRange

ClutchesEngaged Pump

Selector Valve Stations - kPa (psi)

A B C D E F G

Lock-up Solenoid — De-energized

N1 1 � 3179kPa/max

(461psi/max)

AllRanges

0 0 2470(358)

0 0 0 0

N2 1 � 0 *2840(419)

0 0 0 0 0

R 1 7 0 *2840(419)

0 0 0 0 2895(420)

1 2 6 0 *2840(419)

0 0 0 *2840(419)

0

Lock-up Solenoid — Energized

1 1 52100± 103kPa

(305± 15psi)

AllRanges

0 2020(293)

0 ** 0 2020(293)

0

2 2 5 2020(293)

0 0 ** 0 2020(293)

0

3 1 4 0 2020(293)

0 ** 2020(293)

0 0

4 2 4 2020(293)

0 0 ** 2020(293)

0 0

5 1 3 0 2020(293)

2020(293)

** 0 0 0

6 2 3 2020(293)

0 2020(293)

** 0 0 0

* ± 225 kPa (± 33 psi)** Pressure determined by requirement to set pump pressure with the

lock-up solenoid energized.

21

NOTICE

Do not shift the transmission into reverse at any input speed other than 600 rpm.

High Idle Lube Flow Check

1. Adjust input flow to 150 ± 4 Lpm (39 ± 1 gpm). Adjust input shaft rotationto 1850 ± 5 rpm. Lock-up solenoid energized, except for (R).

2. Lube flow must be:

Range Flow Rate

R 128 ± 4 Lpm (33.9 ± 1 gpm)

1 127 ± 4 Lpm (33.5 ± 1 gpm)

2 124 ± 4 Lpm (32.6 ± 1 gpm)

3 126 ± 4 Lpm (33.2 ± 1 gpm)

4 123 ± 4 Lpm (32.4 ± 1 gpm)

5 116 ± 4 Lpm (30.6 ± 1 gpm)

6 115 ± 4 Lpm (30.3 ± 1 gpm)

22

Notes

23

For information on service tools or shop supplies

contact Caterpillar Service Technology Group on:

Caterpillar Service Technology

100 N.E. Adams Street

Peoria, Illinois 61629-9110

1-800-542-8665 (USA)

1-800-541-8665 (Illinois)

1-800-523-8665 (Canada)404435 (Telex)

1-309-675-6618 (Fax)

or

Caterpillar Service TechnologyCaterpillar Overseas S. A.

P.O. Box 6000

1211 Geneva 6

Switzerland

41 (22) 849 40 36 (Geneva Phone)

41 (22) 849 45 44 (Geneva Fax)413323 (Geneva Telex)

CATOVERSEA (Geneva Cable)

36CSTG (COSA E-Mail Address)

©1998 CaterpillarAll Rights Reserved

NEHT6001-04 Printed in U.S.A.