Device and principle of operation

Compressors PK-1.75A; PC-3.5A; PK-5.25A – two-stage piston with a V-shaped arrangement of cylinders and air cooling.

Compressor housings 1 (Fig. 1, 2, 3) are cast iron with four mounting feet.

The front part of the housing is closed with a removable cover 21, in which one of the crankshaft bearings is installed. On the sides of the hull there are hatches for access to internal parts.

Cast iron cylinders are attached to the body on studs, located in two vertical planes at an angle of 90 0 to each other.

Crankshaft 17 steel forged or cast from high-strength cast iron VCh-60

GOST 7293-85 with counterweights, rotates on ball bearings and has a system of channels for the passage of lubrication. A sleeve with a square hole is pressed into the end of the shaft to drive the oil

pump 13.

The connecting rods and liners of all cylinders are the same, borrowed from the engine of the GAZ-51 car.

In the lower split head of the connecting rod, two thin-walled liners filled with babbit are installed.

Table 3 Inserts used on GAZ-51 vehicles (standard and repair dimensions)
Insert number Insert diameter, mm Quantity (halves of the liner)
PK-1.75A PK-3.5A PK-5,25A
VK-51-1000104-B1 51.50
VK-51-1000104-BR 51.45 » » »
VK-51-1000104-BP 51.25 » » »
VK-51-1000104-DR 51.00 » » »
VK-51-1000104-ER 50.75 » » »
VK-51-1000104-ZHR 50.50 » » »
VK-51-1000104-IR 50.25 » » »


50.00 » » »

When assembling the compressor, the first row of connecting rods (from the side of the compressor drive) is installed so that the displacement of the rods relative to the axis of the lower head is directed towards the drive, the rest – towards the compressor oil pump.

Low-pressure aluminum pistons (Fig. 4) and high-pressure cast-iron pistons (Fig. 5) are attached to the upper heads of the connecting rods with the help of piston pins.

Four piston rings are installed on each piston: two upper ones are compression rings, two lower ones are oil scraper rings.

Fig. 5 Connecting rod and piston group HPC 1 – connecting rod; 2 – HP piston; 3 – finger; 4 – retaining ring; 5 – oil scraper ring; 6 – compression ring.
Fig. 4 Connecting rod and piston group of LPC 1 – connecting rod; 2 – piston ND; 3 – finger; 4 – retaining ring; 5 – oil scraper ring; 6 – compression ring.

The valve boxes of the LPC (Fig. 6) and HPC (Fig. 7) are attached to the upper flanges of the cylinders on studs, together with the valves of the I and II stages, respectively.

The compressor is equipped with band valves with elastic limiters (Fig. 8).

The air sucked in by the compressor is cleaned in an air filter with a resonator connected to the low pressure box by a suction manifold. Piryatin-Vola type filter element

72-75 TU.U.19475102-001-95.

After being compressed in the low pressure cylinder, the air is cooled in the intermediate heat exchanger.

Fig. 6 LPC valve box body and valve 1 – LPC valve box body; 2 – 1st stage valve assembly; 3 – gasket.
Fig. 7 HP valve box body and valve 1 – HP valve box body; 2 – 2nd stage valve assembly; 3 – gasket.

The heat exchanger is equipped with a safety valve 7 (Fig. 1, 2, 3), adjusted to a pressure of 4.5 kgf/cm 2 . The valve is installed on the heat exchanger housing from the LPC side.

Fig. 8 Valve assembly 1 – valve board; 2 – plate; 3 – spring

The heat exchangers are blown by the fan 15, mounted on the bracket 16. The four-bladed fan impeller is enclosed in a protective casing and rotates on two ball bearings. The fan is driven by a V-belt from a pulley made on the drive coupling. The compressor has a belt tensioner.

The compressor lubrication system is combined. Under pressure, the connecting rod journals of the crankshaft are lubricated, the remaining parts are lubricated by splashing. The fan bearings are grease lubricated.

Oil is poured into the compressor housing through the hole for oil indicator 2. It is allowed to fill in through the hole for breather 14. Oil is drained from the housing through the hole closed by plug 22. The oil level is checked by oil indicator 2 when it is wrapped. Before starting in cold weather (at temperatures below 5 0 C), the oil in the compressor must be heated with a heater to a temperature of at least 5 0 C. In the absence of a heater, fill the compressor with oil heated to a temperature of 50 0 C. Lubrication is supplied by oil pump 13. The oil is cleaned by filter 12.

Lubrication enters the crankshaft of the compressor through the hollow roller 4 of the pump (Fig. 9). A pressure reducing valve 8 is installed on the cover of the oil pump, which regulates the oil pressure.

The oil pump consists of a cover 1, a body 2 and a flange 3 connected by four studs and centered by two pins.

Roller 4 rotates in two bushings, the square end of the roller is designed to connect it to the crankshaft, into which a bushing with a square hole is pressed.

The operation of the lubrication system is controlled by the readings of the manometer. The oil pressure at the rated speed must not be lower than 1.7 kgf/cm2 .

To eliminate fluctuations in the pressure gauge needle (due to the pulsating oil supply by the pump), the pressure gauge assembly has a hole with a diameter of 0.5 mm and a tap. The normal position of the faucet is closed.

The communication of the internal cavity of the compressor housing with the atmosphere is carried out through the breather 14 (Fig. 1, 2, 3), which has a check valve and a filter packing.

The crankshaft of the compressor is driven through the sleeve-pin coupling 20.

Alignment of the driven compressor should ensure that the compressor runs smoothly. The mismatch between the axes of the compressor and the motor must be no more than 0.1 mm in any plane of measurement.

When installing a driven compressor, a gap of 15 mm between the coupling halves must be maintained to allow the replacement of the fan drive belt without disturbing the installation.

The normal direction of rotation of the compressor shaft should be clockwise when viewed from the drive end. If, at the request of the customer, the compressor is supplied with a counterclockwise rotation of the shaft, a note about this is made in the passport.

A safety valve with a throughput equal to 100% of the compressor’s nominal capacity must be installed on the discharge pipeline from the compressor, adjusted to a response pressure that exceeds the nominal pressure in the 1st stage by 1 kgf / cm 2 .

Fig. 9 Oil pump 1 – cover assembly; 2 – body; 3 – flange assembly; 4 – roller; 5 – spring; 6 – pin; 7 – blade; 8 – pressure reducing valve; B – oil inlet; C – oil output; D – to the pressure gauge.


Table 4 Contents
No. p / p Name (designation) Quantity
Compressor PK-1.75A; PC-3.5A; PK-5.25A (required underline) PCS.
Spare parts designed to ensure the normal operation of the compressor during the warranty period set
Technical documentation
Operation manual copy.
Form copy.
Passports for the main components in the scope of delivery set


1. In the set of delivery of compressors, the leading half-coupling of the pin-sleeve coupling 20

(fig. 1, 2, 3) is available only by separate order.

2. The compressors are supplied with an oil heater TEN-80V13.5 / 0.5Z 220 GOST 13268-88 (220V, 0.5 kW, 96.92 Ohm) or TEN-80V13.5 / 0.5Z 110 GOST 13268-88 (110V, 0.5 kW, 24.2 Ohm) is supplied by a separate order of the consumer.

As a tool, standard keys, screwdrivers, etc. are used. ATTENTION! The use of homemade locksmith tools is STRICTLY FORBIDDEN!

JSC “PTMP” provides spare parts at the request of the consumer in the required quantity. The warranty period is preserved only when original spare parts manufactured by PTMZ JSC are used.


Be First to Comment

Leave a Reply

Your email address will not be published.