The control system allows you to change the air pressure in the tires from the driver's seat, both in the parking lot and while the car is moving, control the tire pressure, and also continue driving the car with minor tire damage.
The tire pressure control system (Fig. 1) consists of a compressor 1. an air cylinder 4, a control valve 7, a pressure regulator 3, a safety valve 5, shut-off air valves for the wheels, sealing blocks installed in the trunnions of the axles (Fig. 2 ), pressure gauge, pipelines and hoses.
The compressor of cars with a tire pressure control system, unlike the compressor of cars without this system, has an unloading cylinder screwed into the threaded hole of the compressor head above the inlet valve.
When the pressure in the system increases to 5–5.5 kg/cm2, the pressure regulator connects the unloading cylinder to the air cylinder, as a result of which air under pressure enters the unloading cylinder and moves the piston 6 (see Fig. 3) down.
The piston rod, having moved down, opens valve 12 and thus connects the cylinder cavity with the engine air filter, as a result of which, during the upward stroke of the compressor piston (compression stroke), air is forced back into the air filter, and not into the system. i.e. the compressor is running without load.
When the pressure in the system drops to 4-4.5 kg/cm2, the pressure regulator connects the unloading cylinder to the atmosphere, the piston 6 with the rod rises under the action of the spring 7 upwards, the inlet valve is released, and the compressor starts to force air into the system again.
The pressure regulator (Fig. 4), together with the unloading cylinder, automatically maintains the pressure in the system in the range from 4-4.5 to 5-5.5 kg/cm2.
When the pressure in the system rises to 5–5.5 kg/cm2, valve 9, under the influence of this pressure, overcoming the force of spring 13, rises until valve 8 is pressed against the seat 6, while the compressed air from the system through the hole "a", the filter 11 and the hole "b" enters the unloading cylinder, as a result of which the air supply to the system stops.
When the pressure in the system drops to 4-4.5 kg / cm2, the regulator spring 13 overcomes the force of compressed air pressure and lowers the balls down, as a result of which the unloading cylinder is disconnected from the system and connected through the holes " b" and "c" with the atmosphere, the compressor inlet valve is released, and the compressor starts to force air into the system.
Relief valve (Fig. 5) is installed in case of failure of the pressure regulator, so it is adjusted to a higher pressure (6 kg/cm2) than the pressure regulator .
Control valve (Fig. 6), allows you to connect the chambers of the wheels with a compressor (when the tires are inflated with air), with the atmosphere (when the pressure in the tires decreases) or lock them (if you want to keep the existing pressure in tires).
Moving relative to body 1 in one direction or another from the middle position, spool 8 can connect cavity "B", which communicates with the wheel chambers, with cavities "A" or "C", which communicate respectively with the compressor and the atmosphere.
The spool of the draft control valve is connected to the valve handle fixed on the fixed floor of the cab.
To switch the tap, lift the handle up and turn it to the desired position; a table indicating the position of the handle is located on the instrument panel
The neutral position of the control valve is fixed by the handle in the bracket, and the pressure increase and pressure decrease positions are fixed by locking the lock ring 6 into the support washer 5 and into the nut 7, respectively.
Air cylinder (see fig. 5) is designed for settling water vapor and oil condensate entering the system from the compressor together with compressed air.
Tire Pressure Regulator Faults and Solutions
- Causes of malfunction
Air leakage with control valve in neutral position and stop wheel valves open:
- Loose connection Frost in pipes and hoses
Tighten loose connections or replace individual elements of the air duct
- The sealing collars of the stuffing box are damaged
Replace packing box or damaged seals
When tires are inflated with air, the pressure in them does not rise to 2.8 kg/cm2 (to normal pressure):
- Large air leak in the system
Find leaks and fix them
- Seizure of the piston of the unloading cylinder due to contamination or distortion of the rod
If necessary, replace the bent piston rod
Disassemble the unloading cylinder, wash it, lubricate its parts with a thin layer of CIATIM-2O1 grease and assemble it.
- The pressure regulator does not connect the unloading cylinder to the atmosphere when the pressure in the system decreases
Disassemble the regulator, wash its parts in gasoline, dry and reassemble.
Adjust regulator if necessary
- Wear of piston rings or compressor cylinder
Repair or replace the compressor
Large amount of oil in condensate drained from air tank:
- Wear of piston rings or compressor cylinder
Repair or replace the compressor
Frequent activation of the safety valve, accompanied by a characteristic sharp sound:
- Faulty pressure regulator or safety valve
Disassemble the regulator or valve, wash it in gasoline and reassemble. Adjust them if necessary
In winter, one or all tires do not inflate or deflate:
- A frozen condenser clogs the air duct
Find the blockage, warm it up and blow it out with air
Tire pressure control system repair
Disassembly, inspection and assembly of tire pressure control system components. Before removing to disassemble the system components, release compressed air from the air cylinder.
The pressure regulator (see fig. 4) must be disassembled in the following order.
Remove cover 1 of the regulator.
Loosen locknut 5, unscrew adjusting cap 2 and remove valve stem 4, spring 13 and support balls 3.
Unscrew the seat b of the regulator, remove the shims 7 and ball valves 8 and 9.
Unscrew the cover 10 of the filter and remove the filter 11.
If damage is found to the surfaces of ball valves or their seats, the parts or the entire regulator must be replaced.
Before assembling, thoroughly rinse all parts of the regulator in gasoline.
The regulator is assembled in the reverse order of disassembly.
After assembly, check the operation of the regulator. It must turn off the compressor at a pressure of 5-5.5 kg/cm2 and turn it on at a pressure of 4-4.5 kg/cm2.
If the regulator does not turn the compressor off and on at the specified pressures, it must be adjusted.
Adjust the regulator as follows:
- turn cap 2 to turn on the compressor at a pressure of 4-4.5 kg/cm2.
When screwing the cap on, the pressure increases, when screwing it off, it decreases. Lock cap with nut 5;
- by changing the number of shims 7, obtain a pressure of 5-5.5 kg / cm2, at which the compressor is turned off.
With an increase in the number of gaskets, the pressure decreases, with a decrease it increases.
Relief valve(see fig. 5). To disassemble the valve, unscrew seat 1 from body 2, remove valve ball 3 and guide rod 5 with spring 6, loosen lock nut 7 and unscrew adjusting screw 8.
If damage is found to a ball valve or its seat in the seat, the ball, seat, or valve assembly must be replaced.
Before assembling, wash the parts of the safety valve thoroughly in gasoline. After assembly, adjust the valve to a pressure of 6 kg/cm2 with screw 8.
Control tap (see Figure 7). To disassemble the control valve, unscrew the lock screw of the nut 7, and then the nut 7, remove the spool 8, glands 4, spacer rings 2, bushings 3 and support washers 5.
Replace damaged glands on the control valve.
Before assembling the parts of the control valve, rinse and lubricate with TsIATIM-201 grease.
Adjust the tension of the stuffing boxes with nut 7. After adjusting the spool must move without jamming, and the valve itself must be airtight.
Oil seal blocks for air supply to the wheels. Of the components of the tire pressure control system, oil seal blocks most often fail.
A faulty unit can be identified by screwing rubber tubes instead of a breather on the front axle stub body and on the rear axle flange and lowering them into the water; air bubbles will appear from the side of the faulty blocks.
Once you have identified the bad oil seal assembly, remove the stub axle and remove it. If the seals are worn, disassemble the unit using a mandrel (Fig. 8) and replace the seals.
Check the newly assembled unit for tightness at a pressure of 3 kg/cm2, using a mandrel with a diameter of 45-0.1mm.
When placing the block of stuffing boxes in the stub axle in the cavity between the cuffs, lay 10g over the entire surface. lubricate the neck of the axle shaft under the oil seals, and fill the free cavities in the stub axle outside the block with grease (grease 1-13 grease GOST 1631-61).
After troubleshooting, check the tire pressure control system for leaks.
With the wheel valves open and the control valve handle in the neutral position, the air pressure drop in the tires should be no more than 1 kg / cm2 for 12 hours.
It should be borne in mind that the tightness must be checked after the tires have cooled down to ambient temperature.