Download 793D Machine System PDF

Title793D Machine System
TagsPump Valve Transmission (Mechanics) Brake Radiator
File Size2.9 MB
Total Pages52
Table of Contents
                            COVER
PREFACE
TABLE OF CONTENTS
NOTES
INTRODUCTION
	Similarities and Differences
ENGINE
	Hydraulic Cooling Fan
REAR AXLE COOLING AND FILTER SYSTEM
STEERING SYSTEM
BRAKE COOLING SYSTEM
AUTOMATIC RETARDER CONTROL (ARC)
CONCLUSION
COLOR CODE
HANDOUT
                        
Document Text Contents
Page 26

The top visual shows the 793C pressure compensated, piston-type pump (1). The steering pump
contains a load sensing controller (2) that works with an accumulator charging valve to monitor
and control steering pump output. When pressure in the accumulators decreases (CUT-IN), the
pump upstrokes and charges the accumulators until the CUT-OUT pressure is reached.

Shown in the bottom visual is the steering pump (3) for the 793D. This pump is mounted on the
backside of the pump drive behind the torque converter housing. Oil is supplied to the pump
through tube (4) coming from the steering tank. Like the 793C, a load sensing controller (5)
controls the pump output but without an external signal line. The pump supply is sent to the
priority valve located on the upper frame, near the right front strut.

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SERV7105-08 - 26 - NPI
Vol. 8, No.1, 2005

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2

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4

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Page 27

The solenoid and relief valve manifold (1) for the 793C, shown in the top visual, connects the
steering pump to the accumulator charging valve (2), to the accumulators, and to the steering
control valve (3). This valve also provides a path to drain for the steering oil. The accumulator
charging valve controls the CUT-IN and CUT-OUT of the steering pump. This valve has been
removed in the 793D steering system.

The bottom visual shows the priority valve manifold on the 793D. This manifold is located on
the frame behind the right steering strut. Oil from the steering pump enters the manifold through
hose (4). The manifold contains a priority valve which gives priority to the steering system.

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SERV7105-08 - 27 - NPI
Vol. 8, No.1, 2005

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Page 51

59

HYDRAULIC SCHEMATIC COLOR CODE

This illustration identifies the meanings of the colors used in the hydraulic schematics and
cross-sectional views shown throughout this presentation.

SERV7105-08 - 51 - NPI
Vol. 8, No.1, 2005

Dark Gray - Cutaway section

Light Gray - Surface color

Red - High pressure oil

Red/White Stripes - 1st pressure reduction

Red Crosshatch - 2nd reduction in pressure

Pink - 3rd reduction in pressure

Red / Pink Stripes - Secondary source oil pressure

Orange - Pilot, signal, or Torque Converter oil

Orange / White Stripes -
Reduced pilot, signal, or TC oil pressure

Green - Tank, sump, or return oil Blue - Trapped oil

Brown - Lubricating oil

Purple - Pneumatic pressure

Orange Crosshatch - 2nd reduction in
pilot, signal, or TC oil pressure.

White - Atmosphere or
Air (no pressure)

Yellow - Moving or activated components

Cat Yellow - (Restricted usage)
Identification of components
within a moving group

Black - Mechanical connection. Seal

Green / White Stripes -
Scavenge Oil or Hydraulic Void

HYDRAULIC SCHEMATIC COLOR CODE

Page 52

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SERV7105-08 - 52 - Handout No. 1
Vol. 8, No.1, 2005 NPI

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