A Hägglunds Viking MB84 hydraulic motor fitted on the winch of an offshore vessel began showing abnormal noise and overheating. TFS overhauled it completely in the workshop — 1,500 kg of radial piston motor — with original spare parts and final bench testing, returning it in 25 days.

Noise and overheating on a Hägglunds Viking MB84 motor

The motor drives the winch of a vessel operating in the offshore sector, where a failure does not simply mean lost production: the vessel has to come back, and the intervention window depends on weather and logistics. The customer reported two symptoms, both typical of a rotary group that has accumulated running hours: increasing noise and overheating in operation.

On a motor of this size, diagnosis is not done by ear. The Viking MB84 is a low-speed, very high torque radial piston motor: 33,780 cm³/rev displacement, roughly 538 Nm of torque for every bar of differential pressure applied — at 350 bar that means over 180,000 Nm at the shaft — running at 35/70 rpm. A component weighing 1,500 kg that requires lifting equipment and a test bench able to take it.

Disassembly and dimensional inspection of the rotary group

The motor was completely stripped down in the workshop. Inspection ruled out structural failure and found widespread service wear on the contact surfaces of the rotary group — the normal condition of a motor that has run many hours under load, and the direct cause of both the noise and the temperature rise.

The decisive step was not observing the wear but measuring it: every component underwent dimensional inspection and the tolerances were certified against the manufacturer’s specifications. This is what separates an overhaul from a repair — without instrumented measurement there is no way to establish which parts are still within tolerance and which must be replaced, and you end up changing either too much or too little.

Overhaul with original Hägglunds spare parts

Based on the measurements, TFS defined the replacement plan and ordered the original Hägglunds spare parts, available in about 10 days. Parts within tolerance were kept; those out of specification were replaced. The motor was then reassembled following the manufacturer’s procedures.

Before delivery the motor went to the test bench, where flow, pressure, temperature, volumetric efficiency, internal leakage and noise were verified. The customer received the complete test report with the measured values: not a statement that a repair took place, but the recorded performance of the component going back into service.

Hägglunds Viking MB84 returned in 25 days, bench tested

The motor went back to the customer 25 days after arriving in the workshop — ten of which spent waiting for the original spare parts — with performance verified on the bench and documented. The winch returned to service without replacing the motor: on a component of this size, and on a vessel in operation, an overhaul avoids both the cost of a new unit and the lead times a replacement would involve.

Why turn to a Hägglunds partner

TFS is a Hägglunds partner and works on the manufacturer’s radial piston motors — CA, CB, CBM, Compact, Atom and Viking series — with access to original spare parts and to the relevant technical specifications. The operational difference comes down to three concrete points:

• Original spare parts, not commercial equivalents: on a motor delivering hundreds of thousands of newton-metres, fit tolerances leave no room for approximation.
• Dimensional inspection with certified tolerances against the manufacturer’s specifications, which determines what actually needs replacing.
• A test bench able to take the component: at 1,500 kg the MB84 is the largest motor testable on the TFS motor bench. Many workshops can strip down a motor this size; few can run it under load before handing it back.

TFS technologies and services involved

• Hägglunds motor repair and overhaul
• Hägglunds – TFS partner
• Hydraulic motors: radial, axial and orbital piston
• Testing and certification on the test bench
• Hydraulics for the marine and offshore sector