Ransomes 67978, 67979, 67980, 67981, 67982, 67983 User manual

Brand: Ransomes

Model: 67978, 67979, 67980, 67981, 67982, 67983

Category: Engine

Type: User manual

4241262-Rev B 5-1

Chapter 5

Hydrostatic Power Train

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Test Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Repair Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Hydraulic Hose, Tube, and Fitting General Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

O-Ring Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Hydraulic Hose Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Hydraulic Service Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Portable In-Line Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Digital Hydraulic Tester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7

Hydraulic Flow Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7

Digital Pressure Gauge Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Hydraulic Hose Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Hydraulic Test Fitting Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8

Blocking Disk Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Component Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Theory of Operation and Sub-Circuit Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Traction Circuit—Neutral Schematic and Theory of Operation

(4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-11

Traction Circuit—Neutral Schematic (4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

Traction Circuit—Forward Schematic and Theory of Operation

(4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14

Traction Circuit—Forward Schematic (4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16

Traction Circuit—Reverse Schematic and Theory of Operation

(4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-19

Traction Circuit—Reverse Schematic (4WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

Traction Circuit—Neutral Schematic and Theory of Operation

(2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-23

Traction Circuit—Neutral Schematic (2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24

Traction Circuit—Forward Schematic and Theory of Operation

(2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-27

Traction Circuit—Forward Schematic (2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28

Traction Circuit—Reverse Schematic and Theory of Operation

(2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-31

Traction Circuit—Reverse Schematic (2WD Models) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-32

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-34

Tests and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36

Neutral Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36

5-2 4241262-Rev B

HYDROSTATIC POWER TRAIN

Field Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-39

Preliminary Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-39

Traction System Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-39

Wheel Motor Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-40

Brake System Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-40

Instrument Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43

Instrument Test Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-43

Charge Pressure Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-44

Traction System Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-45

Traction Pump Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-47

Front Wheel Motors Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-51

4WD Valve Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-55

Rear Wheel Motors Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-57

Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-60

Drive Shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-60

Traction Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-61

Brake Release Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-67

4WD Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-69

Front Wheel Motor (Earlier Machines) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-71

Front Wheel Motor (Later Machines) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-81

Front Axle Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-94

Rear Wheel Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-96

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-3

Specifications

Test Specifications

Repair Specifications

Specification

Traction Pump Flow gpm (lpm) 38.3 (145) at 3150 rpm

Forward System Relief Pressure—

Machine Serial Numbers Ending 1651 Through 2499

psi (bar) 3625 ± 10% (250 ± 10%) at 3150 rpm

Forward System Relief Pressure—

Machine Serial Numbers Ending 2500 and Up

psi (bar) 4350 ± 10% (300 ± 10%) at 3150 rpm

Reverse System Relief Pressure

psi (bar) 3625 ± 10% (250 ± 10%) at 3150 rpm

Charge Pressure

psi (bar) 315 ± 10% (22 ± 10%) at 3150 rpm

Hydrostatic Leakage Percentage Ranges 0–10% = Good

11–20% = Marginal

21% and Beyond = Bad

Specification

Drive Shaft Mounting Screw Torque lb-ft (N·m) 35–40 (47–54)

Traction Pump—Test Port Fitting Torque

lb-ft (N·m) 17 (23)

Traction Pump—Return Tube Fitting Torque

lb-ft (N·m) 80 (108)

Traction Pump—Charge Filter Tube Fitting Torque

lb-ft (N·m) 60 (81)

Traction Pump—Ports “A” and “B” Fitting Torque

lb-ft (N·m) 100 (135)

Traction Pump—System Relief Valves Torque

lb-ft (N·m) 130 (176)

Traction Pump—Charge Pressure Relief Screw

Torque

lb-ft (N·m) 80 (108)

Traction Pump—Tow Valve Torque

lb-ft (N·m) 15 (20)

Traction Pump—Front Cover Screw Torque

lb-ft (N·m) 43 (58)

Traction Pump—Cover Plate Screw Torque

lb-ft (N·m) 57 (77)

Traction Pump—Auxiliary Pad Screw Torque

lb-ft (N·m) 32 (43)

Traction Pump—Case Outlet Plug Torque

lb-ft (N·m) 85 (115)

Traction Pump—Plug Torque

lb-ft (N·m) 15 (20)

Traction Pump—Servo Piston Cover Plug Torque

lb-ft (N·m) 27 (37)

Traction Pump—Servo Piston Cover Screw Torque

lb-ft (N·m) 11 (15)

Traction Pump—Seal Nut Torque

lb-ft (N·m) 27 (37)

Traction Pump—EDC Mounting Screw Torque

lb-ft (N·m) 10 (14)

Traction Pump—Filtration Cover Screw Torque

lb-ft (N·m) 22 (30)

Traction Pump—Filtration Cover Plug Torque

lb-ft (N·m) 27 (37)

Brake Release Valve—Coil Nut Torque

lb-in. (N·m) 33–53 (4–6)

Brake Release Valve—Ports “ST” and “BR” Fitting

Torque

lb-ft (N·m) 17 (23)

Brake Release Valve—CHG and DRN Ports Fitting

Torque

lb-ft (N·m) 17 (23)

Brake Release Valve—Direction Control Valve Torque

lb-ft (N·m) 30–35 (40.7–47.5)

5-4 4241262-Rev B

HYDROSTATIC POWER TRAIN

Brake Release Valve—Direction Control Valve Nut

Torque

lb-in. (N·m) 40–60 (4.5–6.8)

Brake Release Valve—Coil Nut Torque

lb-in. (N·m) 35–53 (4–6)

Brake Release Valve—Solenoid Valve Torque

lb-ft (N·m) 26–30 (35.3–40.7)

Brake Release Valve—Relief Valve Torque

lb-ft (N·m) 20–25 (27.1–33.9)

Brake Release Valve—Check Valve Torque

lb-ft (N·m) 20–25 (27.1–33.9)

4WD Valve—Ports “LRF,” “LRR,” “RRF,” and “RRR”

Fitting Torque

lb-ft (N·m) 110 (149)

4WD Valve—Ports “LF” and “RF” Fitting Torque

lb-ft (N·m) 110 (149)

4WD Valve—DRN Port Fitting Torque

lb-ft (N·m) 25 (34)

4WD Valve—REV Port Fitting Torque

lb-ft (N·m) 160 (217)

4WD Valve—Check Valve Torque

lb-ft (N·m) 30–35 (40.7–47.5)

4WD Valve—Hot Oil Shuttle Torque

lb-ft (N·m) 30–35 (40.7–47.5)

4WD Valve—Relief Valve Torque

lb-ft (N·m) 30–35 (40.7–47.5)

Front Wheel Motor—Mounting Screw Torque—

Machine Serial Numbers Ending 1651 Through 2499

lb-ft (N·m) 85–95 (115–129)

Front Wheel Motor—Mounting Flange-to-Bearing

Housing Screw Torque—

Machine Serial Numbers Ending 1651 Through 2499

lb-ft (N·m) 27 (37)

Front Wheel Motor—Case Drain and Brake Release

Port Fitting Torque—

Machine Serial Numbers Ending 1651 Through 2499

lb-ft (N·m) 15 (20)

Front Wheel Motor—Inlet and Outlet Port Fitting

Torque—

Machine Serial Numbers Ending 1651 Through 2499

lb-ft (N·m) 110 (149)

Front Wheel Motor—End Cover Screw Torque—

Machine Serial Numbers Ending 1651 Through 2499

lb-ft (N·m) 52 (70)

Front Wheel Motor—Mounting Nut Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 90 (122)

Front Wheel Motor—Case Drain Fitting Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 30 (41)

Front Wheel Motor—Brake Release Port Fitting

Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 17 (23)

Front Wheel Motor—Inlet and Outlet Port Fitting

Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 90 (122)

Front Wheel Motor—Bearing Support Rotation

Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 8.85 ± 30% (12 ± 30%)

Front Wheel Motor—Valving Cover–to–Cam Ring

Screw Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 61 ± 10% (83 ± 10%)

Front Wheel Motor—Brake Housing–to–Valving Cover

Screw Torque—

Machine Serial Numbers Ending 2500 and Up

lb-ft (N·m) 107 ± 10% (145 ± 10%)

Front Axle—Mounting Screw Torque

lb-ft (N·m) 185–225 (251–305)

Specification

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-5

Rear Wheel Motor—Mounting Screw Torque lb-ft (N·m) 90–100 (122–136)

Rear Wheel Motor—Inlet and Outlet Port Fitting

Torque

lb-ft (N·m) 90 (122)

Rear Wheel Motor—Case Drain Fitting Torque

lb-ft (N·m) 15 (20)

Rear Wheel Motor—Housing Screw Torque

lb-ft (N·m) 36–37 (49–50)

Specification

5-6 4241262-Rev B

HYDROSTATIC POWER TRAIN

Hydraulic Hose, Tube, and

Fitting General Instructions

O-Ring Installation

• Always install new O-rings.

• On hoses with O-ring fittings, make sure O-rings are

properly seated before tightening.

• O-rings should be lubricated with the fluid to be used

in the system prior to assembly.

Boss Fitting O-Ring Installation

O-Ring Seal Kits

• SAE Boss O-Ring Kit Jacobsen PN 5002452

• O-Ring Face Seal (ORS) O-Ring Kit PN 5002454

• Common O-Ring Sizes Kit PN 5002453

Replacement O-Rings for ORS (Face Seal)

Fittings

Replacement O-Rings for O-Ring Boss

Fittings

Hydraulic Hose Installation

Hold the fixed portion of the hose coupling with one

wrench; use a second wrench to tighten or loosen the

hose nut. This will avoid damaging the fitting seal. When

tightening a hose, do not permit the hose to twist; hold

the hose in a normal straight position.

When installing hoses, place fittings at angles to avoid

contact with fixed parts when turning. Make sure hoses

are assembled to proper “A” and “B” ports on

components.

Hydraulic Hose and Tube Torque Values

1 Tubing O.D. or Hose I.D. 2 O-Ring 3 Thread Size

ORS (Face Seal)

Tube Size

ORS (Face Seal)

O-Ring Size

Jacobsen

Part

Number

4 11 339908

6 12 339909

8 14 339910

10 16 339911

12 18 339912

16 21 339913

20 25 339914

24 29 339915

TN4075

TN4097

Tubing O.D.

or Hose I.D.

Thread

Size

Jacobsen Part

Number

1/8 5/16-24 459290

3/16 3/8-24 459291

1/4 7/16-20 339896

5/16 1/2-20 459293

3/8 9/16-18 339897

1/2 3/4-16 339898

5/8 7/8-14 339899

3/4 1-1/16-12 339900

7/8 1-3/16-12 459296

1 1-5/16-12 339901

1-1/4 1-5/8-12 339902

1-1/2 1-7/8-12 339903

2 2-1/2-12 459300

Size lb-ft N·m

Dash Fractional Min Max Min Max

-4 1/4 10121416

-6 3/8 18202427

-8 1/2 32404354

-10 5/8 46 56 60 75

-12 3/4 65 80 90 110

-16 1 92 105 125 240

-20 1-1/4 125 140 170 190

-24 1-1/2 150 180 200 246

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-7

Hydraulic Service Tools

NOTE

The hydraulic service tools listed here can be obtained

from K-Line Industries at http://klineind.com.

Portable In-Line Filter

Part Number JAC5097

When hydraulic components fail internally, debris from

the failed component can spread throughout the

hydraulic system and cause additional damage.

This situation can be magnified when dealing with a

closed-loop traction system, where oil is not filtered. In

the event of a traction system component failure, it is

recommended that all traction system components be

disassembled and cleaned, or filtered using a portable

in-line filter available through your Jacobsen Dealer. The

portable in-line filter should also be used when testing

hydraulic systems or after replacing a failed component.

IMPORTANT

Always install the in-line filter so oil flows through

the filter before entering a component. Once filtering

has begun, never reverse the flow of oil, or debris

will re-enter the system.

Digital Hydraulic Tester

Part Number AT40031

Features

• Flow up to 100 gpm (379 lpm)

• Pressure up to 6000 psi (414 bar)

• Temperature up to 250° F (120° C)

• Digital display for flow and temperature

• Analog display for pressure

• Flow accuracy 1% of full scale

Hydraulic Flow Meter

Part Number AT40002

Features

• Glycerin filled pressure gauge

• Precision needle-type load valve

• 4–40 gpm (15–15 lpm) flow range

• Pressure up to 5000 psi (345 bar)

• -12 port size

TN4286

TN4288

TN4287

5-8 4241262-Rev B

HYDROSTATIC POWER TRAIN

Digital Pressure Gauge Kit

Part Number JAC5106

Features

• Quick disconnect fittings

• Pressure up to 5000 psi (345 bar)

• Includes one 5 ft (152 cm) hose

Hydraulic Hose Kit

Part Number JAC5001H

NOTE

This hydraulic hose kit is intended to be used with the

JAC5001A Hydraulic Test Fitting Kit.

Contents

• Two 8 ft (244 cm) 12 ORFS (F) x 10 ORFS (F) hoses

• Four 8 ft (244 cm) 10 ORFS (F) x 10 ORFS (F) hoses

• Two 8 ft (244 cm) 8 ORFS (F) x 10 ORFS (F) hoses

Hydraulic Test Fitting Kit

Part Number JAC5001A

NOTE

For detailed component descriptions and sizes, please

see the K-Line Industries website at http://klineind.com.

Contents

• Twenty ORFS tee fittings in five sizes

• Eight ORFS 90° elbow fittings in four sizes

• Forty ORFS caps in five sizes

• Forty ORFS plugs in five sizes

• Six ORS reducer adapters in three sizes

• Sixteen ORS adapters in four sizes

• Eight blocking disks in four sizes

• Three JIC tee fittings in three sizes

• Three 4 in. (102 mm) jumper hoses in three sizes

• One ORS/male NPTF adapter

• One vented bushing

• One copper tube assembly

Blocking Disk Set

Part Number JAC5001-1

NOTE

This blocking disk set is part of the JAC5001A Hydraulic

Test Fitting Kit.

Contents

• Two -6 blocking disks

• Two -8 blocking disks

• Two -10 blocking disks

• Two -12 blocking disks

• Two -16 blocking disks

TN4290

TN4289

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-9

Component Location

See Figure 5-1.

Figure 5-1: Component Location—Left Side

1 Brake Release Valve 3 Gear Pump 5 Rear Axle Motors 7 Front Axle Motors

2 Hydrostatic Pump 4 4WD Valve 6 Drive Shaft

TN3586,TN3628,TN3629, TN3642

5-10 4241262-Rev B

HYDROSTATIC POWER TRAIN

Page Intentionally Blank

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-11

Theory of Operation and

Sub-Circuit Schematics

Traction Circuit—Neutral Schematic

and Theory of Operation

(4WD Models)

System Conditions:

• Engine running

• Park brake switch in the on position (park brake

engaged)

• Traction pedal in the neutral position

Charge Pressure Circuit

The traction pump and gear pump are both driven by the

engine. Section 2 of the gear pump provides charge

pressure oil for the rear reel circuit and the traction pump.

Hydraulic oil is drawn from the hydraulic tank through a

100-mesh screen, and enters the gear pump, supplying

oil to all three pump sections. Oil from section 2 of the

gear pump is routed through the rear reel valve to the

charge filter.

The charge filter uses a 10-micron filter to remove debris

from the oil. In the event of the charge filter becoming

plugged, a 25 psi (1.7 bar) pressure switch will activate

the “Low Hydraulic Oil Filter” message and LED warning

light on the LCD display, and the charge filter will be

bypassed. Charge pressure oil is then routed to the

hydrostatic traction pump. Charge pressure oil is also

routed to the CHG port of the brake release valve.

Traction Pump Circuit

With the traction pedal in the neutral position, the EDC

(electronic displacement control) valve is in the neutral

position and oil pressure in both pilot lines to the control

sleeve is equal. Since pressure is equal on both sides of

the control sleeve, the control sleeve is centered in the

neutral position. Oil is not supplied to the servo pistons

and no movement of the swashplate occurs. The charge

oil is supplied to the closed-loop traction circuit via the

check valves and exits the traction pump at ports “A” and

“B.” Oil from port “A” is routed in parallel to the front

wheel motors.

Oil from port “B” is routed to the REV port of the 4WD

valve. The oil flows against the hot oil shuttle and is then

routed in parallel against the RRF and LRF check valves

to the rear wheel motors.

Oil exiting the right rear motor flows against the RRF

check valve, against the 400 psi (28 bar) LF relief valve

and pilot line of the LF relief valve, against the 400 psi

(28 bar) RF relief valve, exits the 4WD valve at port “LF,”

and is routed to the left front wheel motor.

Oil exiting the left rear motor flows against the LRF check

valve, against the pilot line of the hot oil shuttle, against

the 400 psi (28 bar) LF relief valve, against the 400 psi

(28 bar) RF relief valve and pilot line of the RF relief

valve, exits the 4WD valve at port “RF,” and is routed to

the right front wheel motor.

Since pressure is equal on both sides of the front wheel

motors, no movement occurs. With the closed-loop circuit

charged with oil, the 315 psi (22 bar) charge pressure

relief valve will open and vent excess oil to the hydraulic

tank.

Hydraulic oil is used to lubricate the internal components

of pumps and motors. This oil is returned via the case

drain lines back to the hydraulic tank.

Park Brake Circuit

The front wheel motors are equipped with multi-disk wet

brakes. The brakes are spring-applied, and released with

pressurized oil controlled by the brake solenoid valve and

the brake release valve.

Towing Mode

The park brake circuit is equipped with a lever-operated

brake release valve to allow the release of the brakes

with a dead engine for towing purposes.

When the brake release lever is moved to the released

position, the oil passage in the brake release valve is

opened to the steering cylinder. This oil pathway

provides a means to release the brakes with the engine

off by turning the steering wheel, routing oil from the

steering circuit to the brake cylinders to release the

brakes.

5-12 4241262-Rev B

HYDROSTATIC POWER TRAIN

Traction Circuit—Neutral Schematic (4WD Models)

See Figures 5-2 and 5-3.

Figure 5-2

1 Return Oil to Steering Unit (Port P) 4 Charge Pressure Oil to Rear Reel Valve (Port P) 7 Return Oil from Rear Wheel Motors Case

Drains, 4WD Valve (DRN Port), and Reel

Motors Case Drains

2 Charge Pressure Oil to 4WD Valve

(REV Port)

5 Return Oil to Front Reel Valve (Port P) 8 Return Oil from Front Reel Valve (Port T)

3 Charge Pressure Oil to Front Axle

Motors

6 Charge Pressure Oil from Rear Reel Valve (Port T) 9 Charge Pressure Oil to Brake Release Valve

(CHG Port)

TN2867

10 Micron

Filter

Traction Pump

Suction

Screen

100 Mesh

25 psi

Switch

Hydraulic Tank

25 psi Crack Bypass

10 Micron

Filter

0.50 ci

Forward

Relief Valve

(See Note)

Charge

Filter

Check

Valve

Check

Valve

123

Return

Filter

Gear

Pump

Reverse

Relief Valve

3625 psi

Tow

Valve

0.50 ci 0.50 ci

2.81 ci

Screen

40 Mesh

Charge

Pressure

Relief Valve

315 psi

25 psi

Crack

Bypass

REV

Test

Port

FOW

Test

Port

Control Sleeve

STRG

Test

Port

M1L1

EDC

10 Micron

Filter

Tank Fill Cap

Assembly

Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

3150 ±50 rpm

0.031 in.

Oil

Cooler

25 psi

Crack

Bypass

Note:

Forward relief valve pressure is 3625 psi for machines with serial numbers ending 1651 through 2499.

Forward relief valve pressure is 4350 psi for machines with serial numbers ending 2500 and up.

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-13

Traction Circuit—Neutral Schematic (4WD Models),

Continued

Figure 5-3

2 Charge Pressure Oil from Traction

Pump (Port B)

6 Charge Pressure Oil to Charge Filter 10 Case Drain Oil from Reel Motors

3 Charge Pressure Oil from Traction

Pump (Port A)

7 Return Oil to Hydraulic Tank 11 Return Oil from Rod End of Steering

Cylinder

4 Charge Pressure Oil from Section 2

of Gear Pump

9 Charge Pressure Oil from Charge Filter

TN2868

4WD

Valve

Relief Valve

400 psi

Brake Release

Valve

Left Front

Wheel Motor

Reverse

Forward

Brake

Solenoid

Valve

RRF

Check

Valve

Hot Oil

Shuttle

Relief Valve

350 psi

Right Front

Wheel Motor

REV LF

Relief

Valve 400

DRN

0.052

in.

LRF

Check

Valve

RRR LRR

RRF LRF

Right Rear

Wheel Motor

Left Rear

Wheel Motor

11.90 ci 11.90 ci

DRN BR

Check

Valve

CHG

Rear Reel Valve

Solenoid

Valve

Backlap

Valve

Rear Reel

Test Port

Charge Pressure Oil

(See Note)

Brake

Cylinder

Brake

Cylinder

(See Note)

Note:

Front wheel motor displacement is 19.23 ci for machines with serial numbers ending 1651 through 2499.

Front wheel motor displacement is 17.09 ci for machines with serial numbers ending 2500 and up.

5-14 4241262-Rev B

HYDROSTATIC POWER TRAIN

Traction Circuit—Forward Schematic

and Theory of Operation

(4WD Models)

System Conditions:

• Engine running

• Park brake switch in the off position (park brake

disengaged)

• Traction pedal in the forward position

Charge Pressure Circuit

The traction pump and gear pump are both driven by the

engine. Section 2 of the gear pump provides charge

pressure oil for the rear reel circuit and the traction pump.

Hydraulic oil is drawn from the hydraulic tank through a

100-mesh screen, and enters the gear pump, supplying

oil to all three pump sections. Oil from section 2 of the

gear pump is routed through the rear reel valve to the

charge filter.

The charge filter uses a 10-micron filter to remove debris

from the oil. In the event of the charge filter becoming

plugged, a 25 psi (1.7 bar) pressure switch will activate

the hydraulic oil filter light icon on the LCD and the

charge filter will be bypassed. Charge pressure oil is then

routed to the traction pump. Charge pressure oil is also

routed to the CHG port of the brake release valve.

Traction Drive Circuit

When the traction pedal is moved to the forward position,

the EDC (electronic displacement control) is moved to

the forward position.

Charge pressure oil is supplied to the 40-mesh screen.

Oil is then routed to the EDC and the control sleeve. With

the EDC in the forward position, oil flows through the

EDC to the control sleeve. Oil pressure from the EDC

pilot lines is greater on the forward side of the control

sleeve and the control sleeve shifts to the forward

position. Oil is then routed to the forward side of the

servo piston and the swashplate is moved to the forward

direction. Oil at operating pressure is routed against the

check valve and forward relief valve, and exits the

traction pump at port “A.” Oil is then routed in parallel to

the front wheel motors, driving the motors in the forward

direction.

Oil exiting the left front wheel motor enters port “LF” of

the 4WD valve and is routed against the 400 psi (28 bar)

RF relief valve, against the 400 psi (28 bar) LF relief

valve and pilot line of the LF relief valve, against the RRF

check valve, and to the right rear wheel motor. Oil exiting

the right rear wheel motor flows against the RRF check

valve, against the hot oil shuttle, exits the 4WD valve at

the REV port, and is returned to the traction pump to

replenish the intake side of the pump.

Oil exiting the right front wheel motor enters port “RF” of

the 4WD valve and is routed against the 400 psi (28 bar)

RF relief valve and pilot line of the RF relief valve, against

the 400 psi (28 bar) LF relief valve, against the pilot line

of the hot oil shuttle, against the LRF check valve, and to

the left rear wheel motor. Oil exiting the left rear wheel

motor flows against the LRF check valve, against the hot

oil shuttle, exits the 4WD valve at the REV port, and is

returned to the traction pump to replenish the intake side

of the pump.

Park Brake Circuit

The front wheel motors are equipped with multi-disk wet

brakes. The brakes are spring-applied, and released with

pressurized oil controlled by the brake solenoid valve and

the brake release valve.

Operating Mode

With the brake release valve in the normal operating

position, the park brake switch off, and traction pedal in

the forward position, charge pressure oil flows through

the brake solenoid valve, through the brake release

valve, and to the brake cylinders in the front wheel

motors, releasing the brakes.

With the brake release valve in the normal operating

position and the park brake switch on, oil from the brake

cylinders is released through the brake release valve,

through the brake solenoid valve, and to the hydraulic

tank, engaging the brakes.

Towing Mode

The park brake circuit is equipped with a lever-operated

brake release valve to allow the release of the brakes

with a dead engine for towing purposes.

When the brake release lever is moved to the released

position, the oil passage in the brake release valve is

opened to the steering cylinder. This oil pathway

provides a means to release the brakes with the engine

off by turning the steering wheel, routing oil from the

steering circuit to the brake cylinders to release the

brakes.

Hot Oil Shuttle

The hot oil shuttle is used to remove hot oil from the

closed-loop traction drive circuit when moving forward.

Oil lost due to venting through the hot oil shuttle is

replenished by return oil from the rear wheel motors.

When driving forward, operating pressure oil is routed to

the pilot line of the hot oil shuttle, shifting the valve spool

and opening the valve. Hot oil from the rear wheel motors

flows through the hot oil shuttle, through the 0.052 in.

(1.3 mm) orifice, and is routed back to the hydraulic oil

tank.

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-15

Circuit Relief

The forward 4WD circuit is protected by the forward relief

valve.

For machines with serial numbers ending 1651 through

2499, the relief valve will open if the pressure rises to

3625 psi (250 bar), allowing oil to dump to the return (low

pressure) side of the circuit.

For machines with serial numbers ending 2500 and up,

the relief valve will open if the pressure rises to 4350 psi

(300 bar), allowing oil to dump to the return (low

pressure) side of the circuit.

5-16 4241262-Rev B

HYDROSTATIC POWER TRAIN

Traction Circuit—Forward Schematic (4WD Models)

See Figures 5-4 and 5-5.

Figure 5-4

1 Return Oil to Steering Unit (Port P) 4 Charge Pressure Oil to Rear Reel Valve (Port P) 7 Return Oil from Rear Wheel Motors Case

Drains, 4WD Valve (DRN Port), and Reel

Motors Case Drains

2 Charge Pressure Oil to 4WD

Valve (REV Port)

5 Return Oil to Front Reel Valve (Port P) 8 Return Oil from Front Reel Valve (Port T)

3 Operating Pressure Oil to Front

Axle Motors

6 Charge Pressure Oil from Rear Reel Valve (Port T) 9 Charge Pressure Oil to Brake Release Valve

(CHG Port)

TN2873

Operating Pressure Oil

Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

10 Micron

Filter

Traction Pump

Suction

Screen

100 Mesh

25 psi

Switch

Hydraulic Tank

25 psi Crack Bypass

10 Micron

Filter

0.50 ci

Forward

Relief Valve

(See Note)

Charge

Filter

Check

Valve

Check

Valve

123

Return

Filter

Gear

Pump

Reverse

Relief Valve

3625 psi

Tow

Valve

0.50 ci 0.50 ci

2.81 ci

Screen

40 Mesh

Charge

Pressure

Relief Valve

315 psi

25 psi

Crack

Bypass

REV

Test

Port

FOW

Test

Port

Control Sleeve

STRG

Test

Port

M1L1

EDC

10 Micron

Filter

Tank Fill Cap

Assembly

3150 ±50 rpm

0.031 in.

Oil

Cooler

25 psi

Crack

Bypass

Note:

Forward relief valve pressure is 3625 psi for machines with serial numbers ending 1651 through 2499.

Forward relief valve pressure is 4350 psi for machines with serial numbers ending 2500 and up.

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-17

Traction Circuit—Forward Schematic (4WD Models),

Continued

Figure 5-5

2 Charge Pressure Oil from Traction

Pump (Port B)

6 Charge Pressure Oil to Charge Filter 10 Case Drain Oil from Reel Motors

3 Operating Pressure Oil from

Traction Pump (Port A)

7 Return Oil to Hydraulic Tank 11 Return Oil from Rod End of Steering

Cylinder

4 Charge Pressure Oil from Section 2

of Gear Pump

9 Charge Pressure Oil from Charge Filter

TN2874

4WD

Valve

Relief Valve

400 psi

Brake Release

Valve

Left Front

Wheel Motor

Reverse

Forward

Brake

Solenoid

Valve

RRF

Check

Valve

Hot Oil

Shuttle

Relief Valve

350 psi

Right Front

Wheel Motor

REV LF

Relief

Valve 400

DRN

0.052

in.

LRF

Check

Valve

RRR LRR

RRF LRF

Right Rear

Wheel Motor

Left Rear

Wheel Motor

11.90 ci 11.90 ci

DRN BR

Check

Valve

CHG

Rear Reel Valve

Solenoid

Valve

Backlap

Valve

Rear Reel

Test Port

(See Note)

Brake

Cylinder

Brake

Cylinder

(See Note)

Note:

Front wheel motor displacement is 19.23 ci for machines with serial numbers ending 1651 through 2499.

Front wheel motor displacement is 17.09 ci for machines with serial numbers ending 2500 and up.

Operating Pressure Oil

Charge Pressure Oil Metered Oil

Inlet or Drain Oil

5-18 4241262-Rev B

HYDROSTATIC POWER TRAIN

Page Intentionally Blank

HYDROSTATIC POWER TRAIN

4241262-Rev B 5-19

Traction Circuit—Reverse Schematic

and Theory of Operation

(4WD Models)

System Conditions:

• Engine running

• Park brake switch in the off position (park brake

disengaged)

• Traction pedal in the reverse position

Charge Pressure Circuit

The traction pump and gear pump are both driven by the

engine. Section 2 of the gear pump provides charge

pressure oil for the rear reel circuit and the traction pump.

Hydraulic oil is drawn from the hydraulic tank through a

100-mesh screen, and enters the gear pump, supplying

oil to all three pump sections. Oil from section 2 of the

gear pump is routed through the rear reel valve to the

charge filter.

The charge filter uses a 10-micron filter to remove debris

from the oil. In the event of the charge filter becoming

plugged, a 25 psi (1.7 bar) pressure switch will activate

the hydraulic oil filter light icon on the LCD and the

charge filter will be bypassed. Charge pressure oil is then

routed to the traction pump. Charge pressure oil is also

routed to the CHG port of the brake release valve.

Traction Drive Circuit

When the traction pedal is moved to the reverse position,

the EDC (electronic displacement control) is moved to

the reverse position.

Charge pressure oil is supplied to the 40-mesh screen.

Oil is then routed to the EDC and the control sleeve. With

the EDC in the reverse position, oil flows through the

EDC to the control sleeve. Oil pressure from the EDC

pilot lines is greater on the reverse side of the control

sleeve and the control sleeve shifts to the reverse

position. Oil is then routed to the reverse side of the

servo piston and the swashplate is moved to the reverse

direction. Oil at operating pressure is routed against the

check valve and 3625 psi (250 bar) reverse relief valve,

and exits the traction pump at port “B.”

Operating pressure oil from port “B” of the traction pump

enters the 4WD valve at the REV port, is routed against

the hot oil shuttle, and is then routed in parallel to the

RRF and LRF check valves, and in parallel to the rear

wheel motors.

Oil flows through the RRF check valve, against the right

rear wheel motor, against the against the LF relief valve

and pilot of the LF relief valve, against the RF relief valve,

and exits the 4WD valve at port “LF.” Oil is then routed to

the left front wheel motor, driving the motor in the reverse

direction.

Oil also flows through the LRF check valve, against the

left rear wheel motor, against the pilot of the hot oil

shuttle, against the LF relief valve, against the RF relief

valve and pilot of the RF relief valve, and exits the 4WD

valve at port “RF.” Oil is then routed to the right front

wheel motor; driving the motor in the reverse direction.

Since pressure is equal on both sides of the rear wheel

motors, the rear wheels are free to rotate but do not

contribute to traction in the reverse direction.

Oil exiting the front wheel motors is returned to the

traction pump to replenish the intake side of the pump.

Park Brake Circuit

The front wheel motors are equipped with multi-disk wet

brakes. The brakes are spring-applied, and released with

pressurized oil controlled by the brake solenoid valve and

the brake release valve.

Operating Mode

With the brake release valve in the normal operating

position, the park brake switch off, and traction pedal in

the reverse position, charge pressure oil flows through

the brake solenoid valve, through the brake release

valve, and to the brake cylinders in the front wheel

motors, releasing the brakes.

With the brake release valve in the normal operating

position and the park brake switch on, oil from the brake

cylinders is released through the brake release valve,

through the brake solenoid valve, and to the hydraulic

tank, engaging the brakes.

Towing Mode

The park brake circuit is equipped with a lever-operated

brake release valve to allow the release of the brakes

with a dead engine for towing purposes.

When the brake release lever is moved to the released

position, the oil passage in the brake release valve is

opened to the steering cylinder. This oil pathway

provides a means to release the brakes with the engine

off by turning the steering wheel, routing oil from the

steering circuit to the brake cylinders to release the

brakes.

Circuit Relief

The reverse side of the traction circuit is protected by the

reverse relief valve. The relief valve will open if the

pressure rises to 3625 psi (250 bar), allowing oil to dump

to the return (low pressure) side of the circuit.

5-20 4241262-Rev B

HYDROSTATIC POWER TRAIN

Traction Circuit—Reverse Schematic (4WD Models)

See Figures 5-6 and 5-7.

Figure 5-6

1 Return Oil to Steering Unit (Port P) 4 Charge Pressure Oil to Rear Reel Valve (Port P) 7 Return Oil from Rear Wheel Motors Case

Drains, 4WD Valve (DRN Port), and Reel

Motors Case Drains

2 Operating Pressure Oil to 4WD

Valve (REV Port)

5 Return Oil to Front Reel Valve (Port P) 8 Return Oil from Front Reel Valve (Port T)

3 Charge Pressure Oil to Front Axle

Motors

6 Charge Pressure Oil from Rear Reel Valve (Port T) 9 Charge Pressure Oil to Brake Release Valve

(CHG Port)

TN2875

Operating Pressure Oil

Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

10 Micron

Filter

Traction Pump

Suction

Screen

100 Mesh

25 psi

Switch

Hydraulic Tank

25 psi Crack Bypass

10 Micron

Filter

0.50 ci

Forward

Relief Valve

(See Note)

Charge

Filter

Check

Valve

Check

Valve

123

Return

Filter

Gear

Pump

Reverse

Relief Valve

3625 psi

Tow

Valve

0.50 ci 0.50 ci

2.81 ci

Screen

40 Mesh

Charge

Pressure

Relief Valve

315 psi

25 psi

Crack

Bypass

REV

Test

Port

FOW

Test

Port

Control Sleeve

STRG

Test

Port

M1L1

EDC

10 Micron

Filter

Tank Fill Cap

Assembly

3150 ±50 rpm

0.031 in.

Oil

Cooler

25 psi

Crack

Bypass

Note:

Forward relief valve pressure is 3625 psi for machines with serial numbers ending 1651 through 2499.

Forward relief valve pressure is 4350 psi for machines with serial numbers ending 2500 and up.

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Ransomes 67978, 67979, 67980, 67981, 67982, 67983 User manual

Brand: Ransomes

Model: 67978, 67979, 67980, 67981, 67982, 67983

Category: Engine

Type: User manual

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Ransomes 67978, 67979, 67980, 67981, 67982, 67983 User manual

Ransomes 67978, 67979, 67980, 67981, 67982, 67983 User manual

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