Hydraulics

Hydraulic Systems / Engineering.

Pump, motor, cylinder and valve overhaul, power pack maintenance, hose manufacturing and system troubleshooting.

Service line 02Hydraulic · Mechanical · ElectricalReport included

Pressure gauge connected to a crane hydraulic circuit — Pressure test

01What we do

Hydraulics is the department that gets the first call on a crane job, because most crane faults show up first as pressure: a hoist that cannot hold its rated load, a slewing motor that overheats, a power pack that trips on temperature.

Hydraulics is the department that gets the first call on a crane job, because most crane faults show up first as pressure: a hoist that cannot hold its rated load, a slewing motor that overheats, a power pack that trips on temperature. We connect gauges at the test points, compare the readings with the circuit diagram and decide whether the problem is a pump, a valve setting, contamination or a mechanical load.

Overhaul work is done in the workshop. Axial piston pumps and motors are stripped, measured, cleaned, fitted with new rotary group parts and seals, and run on a test bench before they go back on board. Cylinders are honed, rods re-chromed or replaced, and seal kits fitted. Valves are cleaned, re-set and tested; worn cartridge valves are replaced.

Hoses are made up on site with crimped fittings to the original specification, so a burst hose on a luffing or hoist circuit does not become a two-day stoppage. We also supply hydraulic components from stock and from manufacturers for Bosch Rexroth, Danfoss, Kawasaki, Parker, Eaton Vickers, Hägglunds and other families.

Two overhauled hydraulic pumps on the workshop floor — Hydraulic pumps02

What to send us

Pump or motor type plate (make, model, displacement, serial)
Circuit diagram or crane manual pages if on board
Oil type and the date of the last filter change
Measured pressures if the crew has a gauge, or the fault as observed

Describe the job

02Scope

What the service covers.

The work items under this service line, as listed by our engineers.

01
Hydraulic Motor OverhaulingAxial and radial piston motors (Hägglunds, Rexroth, Kawasaki Staffa, Danfoss, Poclain): strip, measure, new rotary group parts, seals, bench test.
02
Hydraulic Pump RepairVariable displacement piston pumps and gear pumps: swash plate, pistons, valve plate, control pistons and compensators repaired or renewed.
03
Hydraulic Cylinder OverhaulingLuffing and boom cylinders: honing, rod chroming, new seal kits, gland and bush renewal, pressure test.
04
Hydraulic Valve RepairDirectional, proportional, counterbalance, relief and brake valves cleaned, re-set and tested; solenoids and coils replaced.
05
Hydraulic Power Pack MaintenancePump, motor, tank, cooler and filter service; oil analysis and flushing; pressure and temperature switches checked.
06
Counterbalance Valve AdjustmentOver-centre valves set to the crane maker's values so loads hold without creep and lower without judder.
07
Hydraulic Hose Manufacturing / ReplacementHoses crimped on site or in the workshop to SAE and EN specifications, with the correct fittings and routing.
08
Hydraulic System TroubleshootingPressure and flow measurements, leak-down tests, contamination checks and circuit diagram review to find the actual cause.
09
Hydraulic Component SupplyPumps, motors, valves, cylinders, filters, accumulators, hoses and fittings, OEM or equivalent, from stock or on order.

On the job

Photos from recent attendances.

Hydraulic control valve block with spring and fittings on a crane — Valve block · on board01

Hand holding a valve cartridge removed from a crane control block — Cartridge removed02

Rexroth valve part held up in front of the hoses of a crane control block — Valve part03

Hydraulic hoses and fittings below a valve block on a crane — Hoses and fittings04

Solenoid connectors and hose lines under a crane control block — Control block lines05

Four black hydraulic motors lined up on a workshop floor — Hydraulic motors06

03Typical jobs

Faults we are called for.

01Load creeps down with the hoist stopped: counterbalance valve, brake and motor leakage measured and corrected.
02Pump noisy and oil hot: suction restriction, aeration, worn rotary group or cooler fault identified by measurement.
03Luffing cylinder weeping at the gland: cylinder removed, honed, new seals and bushes, pressure tested and refitted.
04Burst hose at the berth: hose made up on site to the original specification and the circuit bled and tested.

04Questions

Asked before the first visit.

Do you test overhauled pumps before returning them?

Every overhauled pump and motor is run on the bench and the flow, pressure and case drain are recorded. The record goes with the unit.

Can a worn cylinder rod be repaired or does it need a new one?

Light scoring is polished out and the rod re-chromed. Deep damage or bending means a new rod, which we manufacture or source to the original dimensions.

Will you supply the hydraulic oil as well?

Yes. We supply hydraulic oils in the viscosity grade the crane maker specifies and arrange flushing when the system is contaminated.

Spare parts / equipment