Cobra 4400 Instruções de Operação descarregar pdf (Página 48)

44

9.7 POSSIBLE FAULTS AND RELEVANT REMEDIES

Fault

Vibrations in hydraulic cylinder and jerkin-

gs at the first manoeuvres.

Vibrations with every functions when the

oil is hot.

Remedy

Perform manoeuvres without loads for

some minutes to warm the oil up.

Add hydraulic oil to the tank.

Operate the control lever carrying the

cylinders to stroke end for some times in

both directions.

Cause

The temperature of the hydraulic oil is

too low.

Lacking of oil in the tank. Air in the hydrau-

lic system.

All the crane movements are very slow,

even when unloaded.

Crane rotation not regular.

The crane does not lift the loads of the

load chart table.

The crane lift the load, but cannot hold it.

Noise coming from articulation points.

The hydraulic legs does not hold under

load.

Suction hose from oiltank crushed or

obstructed.

The pump is drawing in air.

The truck is not correctly levelled.

Worn slewing motor.

Defective pump.

Uncorrect settings of the valves.

Hydraulic cylinder sealings are worn.

Uncorrect settings of the valves.

Hydraulic cylinder sealings are worn.

Lacking of lubrication.

Defective holding valves.

Worn sealings in the stabilizer cylinder.

Replace or clean the suction hose.

Check that the relevant fittings are well

tightened.

Level the truck.

Replace slewing motor.

Replace the pump.*

Adjust valve settings.*

Replace worn sealings.*

Adjust valve settings.*

Replace worn sealings.*

Grease articulation points.

Clean or replace holding valves.*

Replace worn sealings.*

The crane locks with boom lifted at end

course.

One or more movements keep on func-

tioning while selecting another function.

Pressure transducer not set.

Setting of general max. pressure valve

too high.

- Solenoid valve jammed in open posi

tion (dirt, working shaving, long inacti

vity periods)

- Manual operator (where foreseen)

activated

Disassemble the casing and move ma-

nually the boom descent valve (EV2B,

Pict.11 - 12).

Check the general max. pressure valve*

- Unlock, clean or in case replace the

solenoid valve cartridge

- Close down the manual operator

The DC electric motor does not run.

DC electric motor overheating.

Truck battery discharged.

Electric connections are damaged.

Burned fuses.

Motor windings are burnt.

Too long running time.

Charge battery.

Check electrical wirings, terminals, con-

nections and their integrity.

Replace fuses.

Replace the electric pump.

Running periods are to be shortened and

their intervals to be elongated.

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