Construction machines are complex hydraulic and mechanical systems, where one malfunction often leads to further problems.
This was the case with the loader Volvo L220E, which came to our service. The operator reported difficulties with the brakes and improper operation of the radiator fan. As it turned out – these two problems were closely related.
Symptoms of failure – low brake pressure and fan not working
While driving, the machine reported low brake pressure messages. Worse still, after warming up, there was a problem with releasing the handbrake. At the same time, the system did not properly start the radiator fan.
Why?
The system in the Volvo L220E works in such a way that the hydraulic pump must first build the appropriate pressure in the brake system. Only after reaching the correct level is oil directed to the fan. If the pressure is not built up, the fan will not receive power and will not start working.
Diagnosis of the hydraulic system
The first measurements with pressure gauges quickly showed that the pump was unable to build pressure above 100 bars, while the correct values should be 130–140 bars. Only adding gas and increasing the pump's efficiency allowed achieving the proper pressure – but in practice, this meant that the pump was worn out and not fulfilling its role.
Dismantling the pump and verification in the workshop
After draining the oil and dismantling the cabin components, we gained access to the hydraulic pump assembly. We were interested in the smallest one – responsible for the brake system and the fan.
Dismantling revealed serious wear:
- control plate – heavily worn, noticeable grooves,
- collaborating cylinder – with visible signs of wear,
- bushings – damaged Teflon layer, replacement necessary,
- control piston and housing elements – heavily worn.
In such a condition, the pump was unable to generate the appropriate pressure.
Decision – replacement with a new pump
After consulting with the client, the decision was made to replace the pump with a new one, available immediately in our warehouse. For the owner, time was of the essence – the machine was needed for daily work, so choosing a new component was the best solution.
Installation and final effect
After installing the new pump and bleeding the system, we conducted tests. The result?
- brake pressure quickly built up to 153 bars,
- the system properly switched to the fan,
- the fan reacted to temperature and increased its speed as expected.
The Volvo L220E loader returned to full functionality, and the operator can safely use the machine.
Summary
The failure in the Volvo L220E loader showed how strongly the brake system and radiator fan are interconnected. A drop in pressure in the brake pump automatically affects the operation of the fan. In this case, the only solution was to replace the worn hydraulic pump.
The entire video can be seen here.
