Hydraulic cylinder repair

The name of the project I work these days is hydraulic cylinder repair.

I have to service a double acting cylinder. There are the most common used cylinders in the hydraulic systems. Pressure can be applied to either port giving power in both directions.

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The cylinder consist of 5 parts: two end caps (a base cap and a bearing cap) with port connections, cylinder barrel, piston and the piston rod.

Check below the piston rod of the cylinder I do repair

Back to hydraulic cylinder repair in the workshop. I got the drawings and I started to check the parts. I received new parts from the store namely: buffer, trust plate, piston head and gland. Also a kit of seals, o-rings and gliding rings was available and ready to use.

The bigger parts mean the buffer, trust plate, cylinder head and gland I had to wash it first and cleaned properly. One by one I put it in a big industrial oven for washing.

Then I had to inspect them for possible damages and also if there was affected by rust. I found rust spots on some parts that I cleaned properly.

Taken the parts to a clean workshop and preparing for assembly.
Most hydraulic faults are caused by dirt. Very small particles can damage seals, abrade surfaces, block orifices and cause valve spools to jam. Hydraulic components should not be dismantled in the dirty conditions found on site.

I started to put the seals on the parts. A difficult part was with a red seals for trust plate and piston head. The rubber was hard to handle but with patience I managed to fix properly.
While fitting an oil seal care should be taken that the spring loaded main lip side faced the oil pressure side. Also ensure that the surfaces that contact the lip of the seal are free from any roughness, scoring, pitting or wear as this may result in fluid leakage or damage to the seal. When fitting the seal, ensure that it is pressed horizontally. In case it is inclined, the seal has a tendency to get deformed, resulting in oil leakage. Also during installation, no hammer blows should be given on the seals directly.

Check some picture with the buffer, piston head and trust plate prepared for cylinder rod assembly.

Next step in the hydraulic cylinder repair job was to assemble the parts. Mounted the gland first then the buffer, by the help of overhead crane. I brought the buffer close to the cylinder rod I balanced and then I pushed it little by little with the pallet truck. The trust plate was place above the piston head and attached to the cylinder rod. Overhead crane was used again for screwing the piston head on the cylinder rod.

Check bellow the result

The cylinder barrel had to be cleaned. It used an electric pressure washer. The trigger gun is put inside a long pipe. On the other end of the long pipe is a special sort of brush which is cleaning very smoothly the inner cylinder barrel.

Next step was locking the piston head on the cylinder rod. I drilled 4 holes and I inserted 4 pins.

Check the picture below

Then with the overhead crane I took the barrel and cylinder rod placed on the conveyor table for assembly.

With the help of conveyor trolleys located on the conveyor I had centered the barrel and the rod and then gentle I inserted the rod inside the cylinder barrel.

Then the gland had to be attached to the cylinder barrel. But before that, two o-rings must be placed on the gland. One o-ring prevents the leakage of oil along the piston rod and the other is a water proof o-ring.
With the big spanner wrench I set and tightened the gland.
Look below to see how it looks.

The pipes and the safety valves it was mounted in place. The pipes and the valves were properly clean painted and tested.

The hydraulic cylinder repair is close to the end. One more step is testing the cylinder at the prescribed pressure accordingly to the maker procedure.

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