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

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5
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
5
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
5
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
5
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
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
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
HYDROSTATIC POWER TRAIN
4241262-Rev B 5-7
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
5-8 4241262-Rev B
HYDROSTATIC POWER TRAIN
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
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
5
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
2
3
7
1
4
5
6
5-10 4241262-Rev B
HYDROSTATIC POWER TRAIN
5
Page Intentionally Blank
HYDROSTATIC POWER TRAIN
4241262-Rev B 5-11
5
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
5
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
A
B
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
M2
M3
M1L1
EDC
L2
M4
M5
1
2
3
4
5
6
7
8
9
10 Micron
Filter
Tank Fill Cap
Assembly
Return Oil
Charge Pressure Oil
Metered Oil
Inlet or Drain Oil
3150 ±50 rpm
0.031 in.
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
5
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
2
3
4
6
7
9
11
4WD
Valve
RF
Relief Valve
400 psi
Brake Release
Valve
RF
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
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
ST
Check
Valve
CHG
Rear Reel Valve
P
A
B
Solenoid
Valve
T
Backlap
Valve
Rear Reel
Test Port
G
Charge Pressure Oil
10
(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
5
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
5
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
5
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
A
B
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
M2
M3
M1L1
EDC
L2
M4
M5
1
2
3
4
5
6
7
8
9
10 Micron
Filter
Tank Fill Cap
Assembly
3150 ±50 rpm
0.031 in.
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
5
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
2
3
4
6
7
9
11
4WD
Valve
RF
Relief Valve
400 psi
Brake Release
Valve
RF
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
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
ST
Check
Valve
CHG
Rear Reel Valve
P
A
B
Solenoid
Valve
T
Backlap
Valve
Rear Reel
Test Port
G
10
(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
5
Page Intentionally Blank
HYDROSTATIC POWER TRAIN
4241262-Rev B 5-19
5
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
5
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
A
B
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
M2
M3
M1L1
EDC
L2
M4
M5
1
2
3
4
5
6
7
8
9
10 Micron
Filter
Tank Fill Cap
Assembly
3150 ±50 rpm
0.031 in.
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.
/