Correct Disassembly Steps of Small Hydraulic Piston Pumps

Disassembly sequence of piston pumps is incorrect, not knowing which part to disassemble first, unable to start;

Parts of piston pumps are not marked according to the disassembly sequence, making it impossible to reassemble in order later;

Parts are disorganized after disassembly, and after a few days, parts are missing, making it impossible to reassemble;

...

Have you also had such an experience while disassembling a piston pump?Feeling a bit embarrassed?

Although disassembling a piston pump appears simple, there are many details that need attention during the process. Many colleagues, especially new ones, as well as some experienced repair technicians, have encountered such issues when disassembling piston pumps.

Today, based on my practical experience, I've summarized the correct disassembly method for a small hydraulic piston pump. This can be referred to for other brands and types of piston pumps as well. Hope it helps you!

Disassembling the Small Hydraulic Piston Pump Control Device

Exploded view of the control elements, as shown below:

1. Loosen the fixing bolts

2. Use a hammer (brass or rubber hammer) to tap the back cover of the rotary body to loosen it and remove the back cover

3. Mark the back cover, measure the protruding length of the bolts, and loosen the self-locking nuts

4. Remove the hex socket bolt

5. Hand-turn the bolt and remove the side cover (ensure hands are clean)

6. Remove the servo piston

Exploded view of the servo piston, as shown below:

7. Use a special tool to compress the spring

8. Use circlip pliers to remove the circlip.

Note: There are compressed springs inside, be careful to prevent injury

Disassembling the Small Hydraulic Piston Pump Charge Pump

Important: After disassembly, be sure to mark the assembly position to facilitate subsequent assembly

Disassembling the Small Hydraulic Piston Pump Main Body

1. Mark the position of the hex socket bolts(1)

    Record the position to which the bolts should be turned(2)

    Turn the hex socket bolts to the marked position(3). This step is crucial.

2. Make marks, then remove the back cover(connecting block)

3. Remove the back cover and port plate

4. (1) Press down the cylinder body

    (2) Remove the fixed hex socket bolts

    (3) Remove the rotary body assembly

Note: Do not scratch the surface of the cylinder body

5. Remove the cylinder body and piston

When disassembling the cylinder body assembly, remove the pistons and return plates together with the compressed springs, and remove the ball joints.

Exploded view of the cylinder body, as shown below:

6. Use self-tapping nuts to screw into the uncovered metal parts (two places in total), then use pliers to pull out the seal.

7. Use a soft hammer or brass rod to gently tap the shaft out.

8. Remove the rocker plate and the bearing.

9. Remove the locating pin of the swash plate bearing.

Disassembly Precautions for Small Hydraulic Piston Pumps

After assembly, all oil ports must be sealed to prevent impurities from entering the pump.

Remember: Seal all oil ports.

All O-rings can deform over time, and they might get damaged during disassembly. Therefore, all O-rings and seals must be replaced during maintenance.

Remember: Replace all seals.

All mating surfaces will experience varying degrees of wear after use, so inspect the wear condition thoroughly.

Remember: Check all mating surfaces for wear and repair the sealing surfaces.

During startup, if the coupling components of the rotating parts are insufficiently lubricated, they can wear or seize up in a very short time. Ensure that oil is added before starting!

Label the components of the small hydraulic piston pump according to the disassembly sequence and arrange them neatly.