Piston pumps are used in various industries such as lifting machinery, construction equipment, metallurgy, mining, shipbuilding, and forging machine tools, within their hydraulic systems. The efficiency of the hydraulic system during operation largely depends on the volumetric efficiency of the piston pump. When the volumetric efficiency drops to 72%, routine maintenance is required, including replacing bearings and worn-out seals. Friction pairs exceeding the fit clearance must be replaced or repaired to improve performance. To extend the lifespan of hydraulic piston pumps, it is essential to pay attention to the following points:

One: The pumps in plunger pumps are divided into two types: pressure feeding and self-priming.

1. Pressure-lubricated hydraulic pumps typically use an oil tank with compressed air, and some are equipped with a replenishing oil pump that supplies pressure oil directly to the hydraulic pump's intake.

2. Self-priming hydraulic pumps have strong self-priming capabilities, eliminating the need for external oil supply. For hydraulic oil tanks supplied by air pressure, after each machine startup, it is necessary to wait until the hydraulic tank reaches the operating pressure before operating the machinery.

The cleaner the hydraulic oil, the longer the lifespan of the hydraulic pump.

Section II: Inspection and Repair of Friction Pairs

According to the replacement standards for components in plunger pumps, when various clearances of the components exceed the allowable limits, the following three points can be referred to for repair:

1. Implementing "Surface Engineering Technology," the method is as follows:

(a) Plating Technology: Applying a layer of hard chrome to the plunger surface.

(b) Brush镀技术: Applying wear-resistant materials to the piston surface.

(c) Thermal spraying or arc spraying or electro-spraying: Applying high-carbon martensitic wear-resistant materials through spraying.

(d) Laser Cladding: Depositing high-hardness, wear-resistant alloy powder onto the piston surface.

2. Cylinder and copper sleeve with a sintered bonding method, repair method as follows:

(a) Utilize grinding rods for the manual or mechanical grinding and repair of cylinder bores.

(b) Re-boring cylinder bores using a coordinate boring machine.

(c) Utilize tap repair for cylinder bore.

3. For cylinder bodies fitted with copper bushes, repair can be achieved by replacing the copper bushes. First, trim a set of piston rods to a uniform size, then polish the outer diameter with 1000-grit sandpaper or higher. Three methods for installing copper bushes in cylinder bodies.

(a) Cylinder body heating and thermal fit or copper sleeve low-temperature freezing extrusion, interference fit assembly.

(b) Utilizing Loctite adhesive bonding assembly, this method requires the copper jacket to have grooves on its outer diameter surface.

(c) Tap cylinder bore, machine copper sleeve outer diameter with threads, apply Loctite adhesive, and screw into assembly.