Hydraulic Trouble Shooting

Stabilizer Pads - 765H, 865H and 965H

The backhoe is supplied with flip-over stabilizer pads as standard equipment. They are suitable for most backhoe work and generally are all that is ever required. However, street pad kits are available as options for Models 765H, 865H and 965H backhoes. These kits bolt to the standard pads and increase the versatility of the backhoe. See Figure 10.

Figure 10

The trouble shooting material presented in this sec- tion is offered as a guide to diagnosing probable caus- es and remedies for general operational problems. Match your problem with the typical problem exam- ples given, and note the numbers given for the possi- ble cause. These numbers correspond with the possi- ble cause and correction paragraphs that follow.

NOTE: When using the following chart, if it is decided that an overhaul of components or pressure adjust- ments are necessary to correct malfunctioning, it is recommended that your dealer make these repairs. He is equipped to do this work.

WARNING

Escaping hydraulic / diesel fluid under pressure can penetrate the skin causing serious injury.

Do not use your hand to check for leaks. Use a piece of cardboard or paper to check for leaks.

Stop engine and relieve pressure before connect- ing or disconnecting lines.

Tighten all connections before starting engine or pressurizing lines.

If any liquid is injected into the skin, obtain med- ical attention immediately or gangrene may result.

Problems and Possible Causes

A. Machine fails to operate when started initially - 1, 2, 5, 7, 16, 24

B. Machine loses power after operating satisfactorily initially - 1, 8, 10, 14, 16, 24

C. Loss of power in lift or crowd cylinder, but other cylinders function properly - 23, 25, 30

Problems and Possible Causes, Continued

D. Loss of power in any one cylinder including lift and crowd - 8, 9, 10, 11, 12, 13, 23, 25, 26

E. Loss of power in swing cylinders, but other cylin- ders functioning properly - 8, 9, 10, 11, 12, 13, 23, 24, 26

F. Maximum swing action cannot be obtained - 12, 15

G. Slow operation of machine (lack of power) all cylinders - 1, 4, 6, 14, 16, 24

H. Spongy or jerking action of cylinders and/or noisy operation - 1, 3, 4, 5

I.Lift, crowd or bucket cylinders drop under load when control spools shifted from neutral - 28, 30

J.Load drops or settles - 8, 10, 13, 26, 28

K.Leaky cylinders - 10, 11, 12, 13

L.Leaky valve - 8, 16, 17, 29

M.Sticky valve spool - 17, 20, 21, 22

N.Unable to push valve spool in - 17, 18, 20, 21, 22

O.Spring centered spools do not return to neutral - 17, 18, 19, 20, 21, 22

Causes and Corrections

1.Low oil supply in reservoir - fill to proper level.

2.No oil supply to machine - oil is not being diverted from the prime mover hydraulic system. Be sure that the proper controls are actuated on the prime mover.

3.Air in system - bleed all circuits of air by operating machine at maximum oil flow and through full movements.

4.Oil viscosity too heavy, or oil is not at operating temperature - use recommended hydraulic fluid. Run machine until oil reaches operating temperature.

5.Pump not running - check pump drive to be sure it is engaged.

6.Insufficient pumping - advance engine throttle.

7.Improper hose connection - IMPORTANT: Be sure inlet and return hoses are hooked up correctly. Improper hook-up will result in damage to the backhoe valve.

8.Loose oil line connections, leaks in line or broken lines - tighten all hose connections and replace any damaged O-rings at leaking O-ring fittings. Check and replace any damaged hoses and lines.

9.Restrictions in oil lines - check and replace any damaged hoses and lines. Check for pinched hoses.

10.Oil is bypassing cylinder piston, scored piston, worn piston packing, or defective piston assembly - replace or rebuild the cylinder; replace damaged parts.

11.Scored piston rods and worn rod guides in cylinder - replace or rebuild the cylinder; replace damaged parts.

Continued