Ransomes 70538, 70539, 70540, 70541 User manual

5

4263110-Rev B 5-1

Chapter 5

Hydrostatic Power Train

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

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

Repair Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

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

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

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

Hydraulic Service Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Portable In-Line Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Digital Hydraulic Tester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6

Hydraulic Flow Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6

Digital Pressure Gauge Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Hydraulic Hose Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Flow Lock Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Hydraulic Test Fitting Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7

Blocking Disk Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Component Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Theory of Operation and Sub-Circuit Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Traction Circuit—Neutral Schematic and Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . 5-9

Traction Circuit—Neutral Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10

Traction Circuit—Forward 4WD Schematic and Theory of Operation . . . . . . . . . . . . . . . . . 5-13

Traction Circuit—Forward 4WD Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14

Traction Circuit—Reverse 4WD Schematic and Theory of Operation . . . . . . . . . . . . . . . . 5-17

Traction Circuit—Reverse 4WD Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18

Traction Circuit—Forward 2WD Schematic and Theory of Operation . . . . . . . . . . . . . . . . . 5-21

Traction Circuit—Forward 2WD Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22

Traction Circuit—Reverse 2WD Schematic and Theory of Operation . . . . . . . . . . . . . . . . 5-25

Traction Circuit—Reverse 2WD Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-26

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-28

Tests and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-30

Neutral Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-30

Traction Pedal Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-32

Weight Transfer Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-33

Field Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-34

Preliminary Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-34

Traction System Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-34

Wheel Motor Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-35

5-2 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Instrument Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36

Instrument Test Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36

Charge Pressure Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-37

Traction System Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-38

Traction Pump and Front Wheel Motors Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-41

4WD Valve and Rear Wheel Motors Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-46

Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-51

Drive Shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-51

Traction Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-53

4WD Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-59

Rear Wheel Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-61

Front Wheel Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-65

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-3

5

Specifications

Test Specifications

Specification

Traction Pump Flow gpm (lpm) 32.8 (124) at 2700 rpm

Forward System Relief Pressure

psi (bar) 4387 ± 10% (302 ± 10%) at 2700 rpm

Reverse System Relief Pressure

psi (bar) 4387 ± 10% (302 ± 10%) at 2700 rpm

Charge Pressure

psi (bar) 313 ± 10% (22 ± 10%) at 2700 rpm

Weight Transfer Valve Pressure Setting (Adjustable)

psi (bar) 30–275 (2–19)

Hydrostatic Leakage Percentage Ranges 0–10% = Good

11–20% = Marginal

21% and Beyond = Bad

5-4 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Repair Specifications

Specification

Drive Shaft—Mounting Screw Torque lb-ft (N·m) 60–65 (81–88)

Drive Shaft—Yoke Screw Torque

lb-ft (N·m) 30–35 (41–47)

Traction Pump—Port “CP” Fitting Torque

lb-ft (N·m) 90 (122)

Traction Pump—Port “T” Fitting Torque

lb-ft (N·m) 110 (149)

Traction Pump—Port “A” Fitting Torque

lb-ft (N·m) 160 (217)

Traction Pump—Port “B” Fitting Torque

lb-ft (N·m) 160 (217)

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—Filtration Cover Screw Torque

lb-ft (N·m) 22 (30)

Traction Pump—Filtration Cover Plug Torque

lb-ft (N·m) 27 (37)

4WD Valve—Check Valve Torque

lb-ft (N·m) 24–26 (32.6–35.4)

4WD Valve—4WD Oil Shuttle Torque

lb-ft (N·m) 46–54 (62.6–73.4)

4WD Valve—Hot Oil Shuttle Torque

lb-ft (N·m) 24–26 (32.6–35.4)

4WD Valve—4WD Reverse Solenoid Valve Torque

lb-ft (N·m) 46–54 (62.6–73.4)

4WD Valve—4WD Solenoid Valve Torque

lb-ft (N·m) 19–21 (25.8–28.6)

4WD Valve—Coil Nut Torque

lb-ft (N·m) 5 (6.8) Maximum

4WD Valve—Ports “1,” “2,” “3,” and “4” Fitting Torque

lb-ft (N·m) 100 (136)

4WD Valve—Ports “A” and “B” Fitting Torque

lb-ft (N·m) 140 (190)

4WD Valve—Port “T” Fitting Torque

lb-ft (N·m) 35 (47)

4WD Valve—Port “CP” Fitting Torque

lb-ft (N·m) 60 (81)

Front Wheel Motor—Case Drain Fitting Torque

lb-ft (N·m) 35 (47.5)

Left Front Wheel Motor—Tee Fitting Torque

lb-ft (N·m) 11 (15)

Front Wheel Motor—Inlet and Outlet Port Fitting

Torque

lb-ft (N·m) 140 (190)

Front Wheel Motor—Valving Cover Screw Torque

lb-ft (N·m) 88 (120)

Rear Wheel Motor—Mounting Screw Torque

lb-ft (N·m) 90 (122)

Rear Wheel Motor—Inlet and Outlet Port Fitting

Torque

lb-ft (N·m) 110 (149)

Rear Wheel Motor—Case Drain Fitting Torque

lb-ft (N·m) 15 (20.3)

Rear Wheel Motor—Front Retainer Screw Torque

lb-ft (N·m) 21 (28)

Rear Wheel Motor—Housing Screw Torque

lb-ft (N·m) 50 (68)

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-5

5

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

1

2

3

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

5-6 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

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

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-7

5

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

Flow Lock Tool

Part Number JAC5102

This adjustable flow lock tool is specifically designed for

use with the HR-9016T mower.

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

TN4291

TN4289

5-8 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Component Location

See Figure 5-1.

Figure 5-1: Component Location—Left Side

1Traction Pump 34WD Valve 5Front Wheel Motor

2 2-Section Pump 4 Rear Wheel Motor

TN4274, TN4139, TN4275, TN4082

1

3

2

5

4

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-9

5

Theory of Operation and

Sub-Circuit Schematics

Traction Circuit—Neutral Schematic

and Theory of Operation

System Conditions:

• Operator in seat

• Engine running

• Park brake released

• Traction pedal in the neutral position

Charge Pressure Circuit

The traction pump, 2-section pump, and 3-section pump

are all driven by the engine. Section 2 of the 2-section

pump provides charge pressure oil through the left front

deck valve for the traction circuit.

Hydraulic oil is drawn from the hydraulic oil tank by

section 2 of the 2-section pump. Before entering the

2-section pump, the inlet oil is filtered by a 100-mesh

screen to remove any debris. Charge pressure oil from

section 2 of the 2-section pump is routed to port “P” of the

left front deck valve. Oil entering port “P” of the left front

deck valve flows through the solenoid valve and out port

“T” of the left front deck valve.

Oil from port “T” of the left front deck valve is routed to

the charge filter. If the charge filter becomes plugged, a

25 psi (1.7 bar) pressure differential switch will activate

the “Hydraulic Filter” light on the instrument panel

warning light gauge and the charge filter will be

bypassed. Charge pressure oil from the charge filter is

routed to port “CP” of the traction pump to fill the

closed-loop traction circuit. Once filled, the 313 psi (21.6

bar) charge pressure relief valve will open, allowing oil to

return to the return manifold, and then to the hydraulic

tank.

Traction Pump Circuit

With the traction pedal in the neutral position, the

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 and to port “B” of the 4WD valve.

Oil from port “B” of the traction pump is routed in parallel

to the front wheel motors and to port “A” of the 4WD

valve. Since pressure is equal on each side of the front

wheel motors, no movement occurs.

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 return manifold, and then to the

hydraulic tank.

5-10 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Traction Circuit—Neutral Schematic

See Figures 5-2 and 5-3.

Figure 5-2

1 Charge Pressure Oil to Front

Wheel Motors

5 Case Drain Oil from Front Wheel Motors 9 Case Drain Oil from Right Rear Wheel Motor

and Return Oil from Piston End of LH Front Lift

Cylinder

2 Charge Pressure Oil to Front

Wheel Motors

6 Return Oil from 4WD Valve (Port T) 10 Return Oil from Steering Unit (Port T)

3 Charge Pressure Oil to Left Front

Deck Valve (Port P)

7 Case Drain Oil from Left Rear Wheel Motor 11 Charge Pressure Oil from Left Front Deck

Valve (Port T)

4 Charge Pressure Oil to 4WD Valve

(Port CP)

8 Case Drain Oil from Front Deck Motors

Traction Pump

Oil

Cooler

Return

Oil Filter

Return

Manifold

100 Mesh

Screen

100 Mesh

Hydraulic Oil Tank

Charge

Filter

Tank Fill Cap

Assembly

Tow

Valve

Charge Pressure

Relief Valve

313 psi

Reverse

Relief

Valve

4387 psi

2.81

ci

B

CP

A

0.036 in.

0.031 in.

T

60 psi

Crack

Bypass

10 Micron

25 psi

Crack

Bypass

10 Micron

Check

Valve

Filter

2.9 psi

Crack

Bypass

Displacement

Control

Valve

CW

CCW

Pump

2-Section

Pump

Check

Valve

Check

Valve

Forward

Relief

Valve

4387 psi

Engine

2700

rpm

Forward

Reverse

25 psi

Crack

Bypass

1

2

3

4

6

7

8

9

10

11

5

3-Section Pump

25 psi

Pressure

Differential

Switch

1.28

ci ci

0.49

21

1.28

ci

1.28

ci ci

1.28

321

TN4035

Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-11

5

Traction Circuit—Neutral Schematic,

Continued

Figure 5-3

1 Charge Pressure Oil from Traction

Pump (Port B)

5 Front Wheel Motors Case Drain Oil to Return

Manifold

8 Front Deck Motors Case Drain Oil to

Return Manifold

2 Charge Pressure Oil from Traction

Pump (Port A)

6 4WD Valve (Port T) Return Oil to Return Manifold 9 Right Rear Wheel Motor Case Drain Oil

and LH Front Lift Cylinder Piston End Oil

to Return Manifold

3 Charge Pressure Oil from 2-Section

Pump (Section 2)

7 Left Rear Wheel Motor Case Drain Oil to Return

Manifold

11 Charge Pressure Oil to Charge Filter

4 Charge Pressure Oil from Charge

Filter

1

2

3

4

6

7

8

9

11

5

L

R

DA

DB

DC

Right Front

Wheel

Motor

4WD Valve

Left

Rear

Wheel

Motor

ci

12.54

ci

12.54

A

BA

B

4WD

Solenoid

Valve

Hot Oil

Shuttle

4WD Oil

Shuttle

A

T

CP

B

1

4

3

2

15.56

cici

15.56

0.059

in.

4WD

Reverse

Solenoid

Valve

Right

Rear

Wheel

Motor

Check

Valve

Left Front

Wheel

Motor

Left

Front

Deck

Valve

Left

Center

Motor

Left

Winglet

Motor

Check

Valve

AB

PD T

Relief Valve

3000 psi

Blade

Brake

Relief

Valve

630 psi

Test

Port

Check

Valve

0.98

ci

0.98

ci

Solenoid

Valve

TN4036

Return Oil

Charge Pressure Oil

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HYDROSTATIC POWER TRAIN

5

Page Intentionally Blank

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-13

5

Traction Circuit—Forward 4WD

Schematic and Theory of Operation

System Conditions:

• Engine running

• Park brake released

• Traction pedal in the forward position

• 4WD switch in the 4WD position

Charge Pressure Circuit

The traction pump, 2-section pump, and 3-section pump

are all driven by the engine. Section 2 of the 2-section

pump provides charge pressure oil through the left front

deck valve for the traction circuit.

Hydraulic oil is drawn from the hydraulic oil tank by

section 2 of the 2-section pump. Before entering the

2-section pump, the inlet oil is filtered by a 100-mesh

screen to remove any debris. Charge pressure oil from

section 2 of the 2-section pump is routed to port “P” of the

left front deck valve. Oil entering port “P” of the left front

deck valve flows through the solenoid valve and out port

“T” of the left front deck valve.

Oil from port “T” of the left front deck valve is routed to

the charge filter. If the charge filter becomes plugged, a

25 psi (1.7 bar) pressure differential switch will activate

the “Hydraulic Filter” light on the instrument panel

warning light gauge and the charge filter will be

bypassed. Charge pressure oil from the charge filter is

routed to port “CP” of the traction pump to fill the

closed-loop traction circuit. Once filled, the 313 psi (21.6

bar) charge pressure relief valve will open, allowing oil to

return to the return manifold, and then to the hydraulic

tank. Charge pressure oil from the charge filter is also

routed to port “CP” of the 4WD valve.

Traction Drive Circuit

When the traction pedal is moved to the forward position,

the displacement control valve is moved to the forward

position.

Charge pressure oil is supplied to the 0.036 in. (0.91 mm)

orifice. Oil is then routed to the displacement control

valve. With the displacement control valve in the forward

position, oil flows through the displacement control valve

and through the 0.031 in. (0.79 mm) orifice to the control

sleeve. Oil is then routed to the forward side of the servo

piston and the swashplate is moved to the forward

direction. This change of the swashplate angle produces

an increase of oil flow on one side of the pump.

Operating pressure oil is then routed to the check valve

and 4387 psi (302 bar) forward relief valve, and exits the

traction pump through port “B.” Oil is then routed in

parallel to the front wheel motors, driving the motors in

the forward direction. Operating pressure oil is also

routed to port “A” of the 4WD valve. Oil exiting the front

wheel motors is returned to the traction pump to

replenish the intake side of the pump.

Charge pressure oil entering port “CP” of the 4WD valve

is routed to the 4WD solenoid valve and to test port “DC.”

Charge pressure oil entering port “CP” is also routed

through the check valve and to the 4WD reverse solenoid

valve and 4WD oil shuttle.

When the 4WD switch is placed in the 4WD position, the

4WD solenoid valve shifts, allowing oil to flow through the

valve. This charge pressure oil is then routed to the pilot

end of the 4WD oil shuttle, causing the valve to shift. With

the valve shifted, operating pressure oil from port “A”

flows through the 4WD oil shuttle, and is routed in

parallel through port “1” of the 4WD valve to the right rear

wheel motor and through port “2” of the 4WD valve to the

left rear wheel motor, driving the rear wheels in the

forward direction.

Oil exiting the rear wheel motors enters the 4WD valve at

ports “3” (right rear wheel motor) and “4” (left rear wheel

motor), and flows through the 4WD reverse solenoid

check valve and exits the 4WD valve at port “B” to

replenish the intake side of the traction pump.

Charge pressure oil from the check valve also flows

through the 4WD reverse solenoid check valve, exiting

the 4WD valve at port “B” to replenish the intake side of

the traction pump. With the 4WD oil shuttle shifted,

charge pressure oil from the check valve to the 4WD oil

shuttle is blocked.

Hot Oil Shuttle

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

closed-loop traction drive circuit when driving either

forward or in reverse. Oil lost due to venting through the

hot oil shuttle is replenished by return oil from the rear

wheel motors and charge oil from port “CP.”

When driving forward, operating pressure oil from port

“A” of the 4WD valve is routed to the pilot line on the

forward side of the hot oil shuttle, shifting the valve spool.

Hot oil from the rear wheel motors and charge oil from

the check valve flows through the 4WD reverse solenoid

valve, through the hot oil shuttle, through the 0.059 in.

(1.5 mm) orifice, and is routed back to the return

manifold, and then to the hydraulic tank.

Circuit Relief

The forward side of the traction circuit is protected by the

forward relief valve. The relief valve will open if the

pressure rises to 4387 psi (302 bar), allowing oil to dump

to the charge side of the circuit.

5-14 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Traction Circuit—Forward 4WD Schematic

See Figures 5-4 and 5-5.

Figure 5-4

1 Operating Pressure Oil to Front

Wheel Motors

5 Case Drain Oil from Front Wheel Motors 9 Case Drain Oil from Right Rear Wheel Motor

and Return Oil from Piston End of LH Front Lift

Cylinder

2 Charge Pressure Oil from Front

Wheel Motors

6 Return Oil from 4WD Valve (Port T) 10 Return Oil from Steering Unit (Port T)

3 Charge Pressure Oil to Left Front

Deck Valve (Port P)

7 Case Drain Oil from Left Rear Wheel Motor 11 Charge Pressure Oil from Left Front Deck

Valve (Port T)

4 Charge Pressure Oil to 4WD Valve

(Port CP)

8 Case Drain Oil from Front Deck Motors

Traction Pump

Oil

Cooler

Return

Oil Filter

Return

Manifold

100 Mesh

Screen

100 Mesh

Hydraulic Oil Tank

Charge

Filter

Tank Fill Cap

Assembly

Tow

Valve

Charge Pressure

Relief Valve

313 psi

Reverse

Relief

Valve

4387 psi

2.81

ci

B

CP

A

0.036 in.

0.031 in.

T

60 psi

Crack

Bypass

10 Micron

25 psi

Crack

Bypass

10 Micron

Check

Valve

Filter

2.9 psi

Crack

Bypass

Displacement

Control

Valve

CW

CCW

Pump

2-Section

Pump

Check

Valve

Check

Valve

Forward

Relief

Valve

4387 psi

Engine

2700

rpm

Forward

Reverse

25 psi

Crack

Bypass

1

2

3

4

6

7

8

9

10

11

5

3-Section Pump

25 psi

Pressure

Differential

Switch

1.28

ci ci

0.49

21

1.28

ci

1.28

ci ci

1.28

321

TN4037

Operating Pressure Oil Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-15

5

Traction Circuit—Forward 4WD Schematic,

Continued

Figure 5-5

1 Operating Pressure Oil from

Traction Pump (Port B)

5 Front Wheel Motors Case Drain Oil to Return

Manifold

8 Front Deck Motors Case Drain Oil to

Return Manifold

2 Charge Pressure Oil to Traction

Pump (Port A)

6 4WD Valve (Port T) Return Oil to Return Manifold 9 Right Rear Wheel Motor Case Drain Oil

and LH Front Lift Cylinder Piston End Oil

to Return Manifold

3 Charge Pressure Oil from 2-Section

Pump (Section 2)

7 Left Rear Wheel Motor Case Drain Oil to Return

Manifold

11 Charge Pressure Oil to Charge Filter

4 Charge Pressure Oil from Charge

Filter

1

2

3

4

6

7

8

9

11

5

L

R

DA

DB

DC

Right Front

Wheel

Motor

4WD Valve

Left

Rear

Wheel

Motor

ci

12.54

ci

12.54

A

BA

B

4WD

Solenoid

Valve

Hot Oil

Shuttle

4WD Oil

Shuttle

A

T

CP

B

1

4

3

2

15.56

cici

15.56

0.059

in.

4WD

Reverse

Solenoid

Valve

Right

Rear

Wheel

Motor

Check

Valve

Left Front

Wheel

Motor

Left

Front

Deck

Valve

Left

Center

Motor

Left

Winglet

Motor

Check

Valve

AB

PD T

Relief Valve

3000 psi

Test

Port

Check

Valve

0.98

ci

0.98

ci

Solenoid

Valve

Blade

Brake

Relief

Valve

630 psi

TN4038

Operating Pressure Oil

Return Oil

Charge Pressure Oil

Inlet or Drain Oil

5-16 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Page Intentionally Blank

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-17

5

Traction Circuit—Reverse 4WD

Schematic and Theory of Operation

System Conditions:

• Engine running

• Park brake released

• Traction pedal in the reverse position

• 4WD switch in the 4WD position

• 4WD reverse switch in the momentary 4WD reverse

position

Charge Pressure Circuit

The traction pump, 2-section pump, and 3-section pump

are all driven by the engine. Section 2 of the 2-section

pump provides charge pressure oil through the left front

deck valve for the traction circuit.

Hydraulic oil is drawn from the hydraulic oil tank by

section 2 of the 2-section pump. Before entering the

2-section pump, the inlet oil is filtered by a 100-mesh

screen to remove any debris. Charge pressure oil from

section 2 of the 2-section pump is routed to port “P” of the

left front deck valve. Oil entering port “P” of the left front

deck valve flows through the solenoid valve and out port

“T” of the left front deck valve.

Oil from port “T” of the left front deck valve is routed to

the charge filter. If the charge filter becomes plugged, a

25 psi (1.7 bar) pressure differential switch will activate

the “Hydraulic Filter” light on the instrument panel

warning light gauge and the charge filter will be

bypassed. Charge pressure oil from the charge filter is

routed to port “CP” of the traction pump to fill the

closed-loop traction circuit. Once filled, the 313 psi (21.6

bar) charge pressure relief valve will open, allowing oil to

return to the return manifold, and then to the hydraulic

tank.

Traction Drive Circuit

When the traction pedal is moved to the reverse position,

the displacement control valve is moved to the reverse

position.

Charge pressure oil is supplied to the 0.036 in. (0.91 mm)

orifice. Oil is then routed to the displacement control

valve. With the displacement control valve in the reverse

position, oil flows through the displacement control valve

and through the 0.031 in. (0.79 mm) orifice to the control

sleeve. Oil is then routed to the reverse side of the servo

piston and the swashplate is moved to the reverse

direction. This change of the swashplate angle produces

an increase of oil flow on one side of the pump.

Operating pressure oil is then routed to the check valve

and 4387 psi (302 bar) reverse relief valve, and exits the

traction pump through port “A.” Oil is then routed in

parallel to the front wheel motors, driving the motors in

the reverse direction. Operating pressure oil is also

routed to port “B” of the 4WD valve. Oil exiting the front

wheel motors is returned to the traction pump to

replenish the intake side of the pump.

Charge pressure oil entering port “CP of the 4WD valve

is routed to the 4WD solenoid valve, test port “DC,” and

the check valve.

When the 4WD switch is placed in the 4WD position, the

4WD solenoid valve shifts, allowing oil to flow through the

valve. This charge pressure oil is then routed to the pilot

end of the 4WD oil shuttle, causing the valve to shift.

Operating pressure oil entering port “B” of the 4WD valve

is routed to the hot oil shuttle, test port “DB,” and the

4WD reverse solenoid valve.

When the 4WD reverse switch is held in the momentary

4WD reverse position, the 4WD reverse solenoid shifts.

With the valve shifted, operating pressure oil from port

“B” flows through the valve and is routed to the check

valve, 4WD oil shuttle, and is then routed in parallel

through port “3” of the 4WD valve to the right rear wheel

motor and through port “4” of the 4WD valve to the left

rear wheel motor, driving the rear wheels in the reverse

direction.

Oil exiting the rear wheel motors enters the 4WD valve at

ports “1” (right rear wheel motor) and “2” (left rear wheel

motor), and flows to the 4WD oil shuttle. With the 4WD oil

shuttle shifted, return oil from the rear wheel motors flows

through the 4WD oil shuttle and is routed to the hot oil

shuttle, test port “DA,” and then exits the 4WD valve at

port “A” to replenish the intake side of the traction pump.

Hot Oil Shuttle

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

closed-loop traction drive circuit when driving either

forward or in reverse. Oil lost due to venting through the

hot oil shuttle is replenished by return oil from the rear

wheel motors.

When driving in reverse, operating pressure oil from port

“B” of the 4WD valve is routed to the pilot line on the

reverse side of the hot oil shuttle, shifting the valve spool.

Hot oil from the rear wheel motors flows through the 4WD

hot oil shuttle, through the 0.059 in. (1.5 mm) orifice, and

is routed back to the return manifold, and then to the

hydraulic tank.

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 4387 psi (302 bar), allowing oil to dump

to the charge side of the circuit.

5-18 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Traction Circuit—Reverse 4WD Schematic

See Figures 5-6 and 5-7.

Figure 5-6

1 Charge Pressure Oil from Front

Wheel Motors

5 Case Drain Oil from Front Wheel Motors 9 Case Drain Oil from Right Rear Wheel Motor

and Return Oil from Piston End of LH Front Lift

Cylinder

2 Operating Pressure Oil to Front

Wheel Motors

6 Return Oil from 4WD Valve (Port T) 10 Return Oil from Steering Unit (Port T)

3 Charge Pressure Oil to Left Front

Deck Valve (Port P)

7 Case Drain Oil from Left Rear Wheel Motor 11 Charge Pressure Oil from Left Front Deck

Valve (Port T)

4 Charge Pressure Oil to 4WD Valve

(Port CP)

8 Case Drain Oil from Front Deck Motors

Traction Pump

Oil

Cooler

Return

Oil Filter

Return

Manifold

100 Mesh

Screen

100 Mesh

Hydraulic Oil Tank

Charge

Filter

Tank Fill Cap

Assembly

Tow

Valve

Charge Pressure

Relief Valve

313 psi

Reverse

Relief

Valve

4387 psi

2.81

ci

B

CP

A

0.036 in.

0.031 in.

T

60 psi

Crack

Bypass

10 Micron

25 psi

Crack

Bypass

10 Micron

Check

Valve

Filter

2.9 psi

Crack

Bypass

Displacement

Control

Valve

CW

CCW

Pump

2-Section

Pump

Check

Valve

Check

Valve

Forward

Relief

Valve

4387 psi

Engine

2700

rpm

Forward

Reverse

25 psi

Crack

Bypass

1

2

3

4

6

7

8

9

10

11

5

25 psi

Pressure

Differential

Switch

1.28

ci ci

0.49

21

3-Section Pump

1.28

ci

1.28

ci ci

1.28

321

TN4039

Operating Pressure Oil Return Oil

Charge Pressure Oil

Metered Oil

Inlet or Drain Oil

HYDROSTATIC POWER TRAIN

4263110-Rev B 5-19

5

Traction Circuit—Reverse 4WD Schematic,

Continued

Figure 5-7

1 Charge Pressure Oil to Traction

Pump (Port B)

5 Front Wheel Motors Case Drain Oil to Return

Manifold

8 Front Deck Motors Case Drain Oil to

Return Manifold

2 Operating Pressure Oil from

Traction Pump (Port A)

6 4WD Valve (Port T) Return Oil to Return Manifold 9 Right Rear Wheel Motor Case Drain Oil

and LH Front Lift Cylinder Piston End Oil

to Return Manifold

3 Charge Pressure Oil from 2-Section

Pump (Section 2)

7 Left Rear Wheel Motor Case Drain Oil to Return

Manifold

11 Charge Pressure Oil to Charge Filter

4 Charge Pressure Oil from Charge

Filter

1

2

3

4

6

7

8

9

11

5

L

R

CP

DB

DC

Blade

Brake

Relief

Valve

630 psi

Right Front

Wheel

Motor

4WD Valve

Left

Rear

Wheel

Motor

ci

12.54

ci

12.54

A

BA

B

4WD

Solenoid

Valve

Hot Oil

Shuttle

4WD Oil

Shuttle

A

T

B

1

4

3

2

15.56

cici

15.56

0.059

in.

4WD

Reverse

Solenoid

Valve

Right

Rear

Wheel

Motor

Check

Valve

Left Front

Wheel

Motor

Left

Front

Deck

Valve

Left

Center

Motor

Left

Winglet

Motor

Check

Valve

AB

PD T

Relief Valve

3000 psi

Test

Port

Check

Valve

0.98

ci

0.98

ci

Solenoid

Valve

TN4040

Operating Pressure Oil

Return Oil

Charge Pressure Oil

Inlet or Drain Oil

5-20 4263110-Rev B

HYDROSTATIC POWER TRAIN

5

Page Intentionally Blank

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Ransomes 70538, 70539, 70540, 70541 User manual

Ransomes 70538, 70539, 70540, 70541 User manual

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