Brake system GAZ-3309 (diesel): diagram, device and features
Brake system GAZ-3309 (diesel): diagram, device and features

The brake system GAZ-3309 (diesel), the diagram of which is shown below, is simple and reliable. It provides timely braking of a truck with high cross-country ability and a very decent load capacity. The arrangement of the driving wheels according to the 4x2 formula is designed mainly for hard surfaces, although it allows you to move quite confidently off-road. Therefore, the brakes must work well in all conditions.

Part of the brake system GAZ-3309
Part of the brake system GAZ-3309

Scheme of the brake system GAZ-3309 (diesel) with air dryer

The circuit itself is shown in the photo below.

Schematic diagram of the brake system GAZ-3309
Schematic diagram of the brake system GAZ-3309
  1. Compressor unit.
  2. HC tank.
  3. Emergency sensor.
  4. Filter.
  5. Rear wheel brake structure.
  6. Sensor.
  7. Pneumatic signal switch.
  8. Muffler.
  9. Drain cock.
  10. Front wheel brake.
  11. Critical pressure indicator.
  12. Air tank.
  13. Return valvetype.
  14. Safety single valve.
  15. Pneumatic booster.
  16. Modulator.
  17. Control valve.
  18. Atmospheric balloon.
  19. Air dryer.
  20. Piston sensor.
  21. Brake valve with two sections.

General Description

When designing a truck that was created almost from scratch, it was decided to develop a radically new scheme of the brake system. The GAZ-3309 diesel engine was equipped with a design that did not depend on previous modifications. The constituent elements of the TS are conditionally divided into three categories:

  1. Working (main) node.
  2. Parking brake.
  3. Spare block.

All systems are aimed at one action - reducing the speed or completely stopping the car, depending on the commands given by the driver. An important factor is that for freight transport the brakes must be as reliable as possible, guaranteeing the vehicle to stop in any situation, in order to avoid an accident with serious consequences.

The main system is called so because it is operated constantly when the car is moving. Any brake design consists of a drive and mechanics. The first node is responsible for activating the system at the right time, and the mechanics create resistance to movement.

Management and appointment

The main control of the brake system of GAZ-3309 cars is the foot pedal. It is installed between the analogues of the clutch and gas. It should be noted that on the predecessors, this element had a very tight release. Updated designcompletely devoid of this drawback, the pedal goes softly and smoothly, which is comparable to foreign analogues.

The truck 3309 combines parking and spare brakes into one set. This made it possible to reduce the number of components with a simultaneous simplification of the design. The so-called "handbrake" serves to keep the vehicle on a slope when starting off or during long parking. Experienced drivers know that this is an important element, since it is very difficult to catch a loaded car without rolling back, even on a slight slope. The parking brake system GAZ-3309 (diesel) is shown below.

Parking brake GAZ-3309
Parking brake GAZ-3309

Scheme is given with explanations:

  1. Retainer.
  2. Lever type handle.
  3. Static drive.
  4. Expanding element.
  5. Brake pads.
  6. Pusher.
  7. Drum mechanism.
  8. Spring.
  9. Finger.
  10. Main drum.


This mechanism consists of a variety of friction parts mounted in direct aggregation with the wheel. The parking analog in this place does not aggregate with the main node, having a separate design. It is mounted on the cardan shaft with fixation when turned on. Drum elements are provided in the device and circuit of the GAZ-3309 (diesel) brake system, since they are considered optimal for the type of trucks in question. In addition to the drum itself, the design includes fixed pads of a tape configuration, pressed against it.

The body part closely interacts with the wheel, rotatingwith him. In the inner part there are brake pads on springs. When you press the pedal, they are pressed against the drum, slowing down its speed. They are fixed on the hub of the car with a bolt fastening that provides maximum effort. The pads are made from an abrasion resistant friction alloy.

Drive part

The drive in the GAZ-3309 (diesel) brake system circuit is needed to control the mechanism with the subsequent performance of certain manipulations. Mechanical and hydraulic working drives are mounted on the truck, which are responsible for the functioning of the parking and main unit. The hydraulic drive was not chosen by chance, as it is considered the best option for a simple truck.

In addition to the above modification, there are also actuators of pneumatic and electric configuration, which have a narrow specialization, and are not used on cars of the series in question. Below, for clarity, the figure shows a wheel brake.

Wheel brake GAZ-3309
Wheel brake GAZ-3309


  1. Brake shoe.
  2. Protection-cap.
  3. Cylinder reservoir.
  4. Piston.
  5. Cuff.
  6. Driven piston.
  7. Tie spring.
  8. Guide bracket.
  9. Brake shield.
  10. Puck.
  11. Nut.
  12. Finger Cam.
  13. Sleeves.
  14. Eccentric plates.
  15. Tags.
  16. Lookout hatch.


Overview of the brakes of GAZ-3307 and 09 trucks will continue to studya kind of alarm system that notifies of a malfunction of the brakes. In addition, the design includes a hydraulic vacuum type amplifier with a reservoir and a shut-off valve. Separate hydraulic circuits are mounted on each axle of the vehicle. This makes it possible, in the event of a failure of one circuit, to ensure the fulfillment of assigned duties, preventing the occurrence of emergencies.

Cylinder tanks are responsible for powering each compartment separately, which is also done for safety purposes. Along the circuits, a built-in brake force controller is provided, which serves to create the required pressure if one of the circuits breaks or an equal pressure adjustment on each wheel is required. Simply put, the device does not double the pressure force in the working circuit. At the same time, the distance of the pedal travel increases, which requires the driver to squeeze it out as much as possible.

Brake Cylinder

A complete review of the GAZ-3307 and 09 truck brakes should include a study of the features of the master brake cylinder. It is activated by pressing the pedal, creating the required pressure in the circuit due to small pistons. This element is halved for each contour. Floating pistons are a modification of the bypass valve. During the free state of the pedal, the TC communicates with the expansion tank.

When you press the pedal, the pistons begin to move, sit in place and overlap tightly. Accordingly, the interaction of the shopping center and the tank stops. During normal daily operation of the truck, the levelbrake mixture is close to the maximum value, especially on new pads and a removed indicator. Below is an image of a brake valve, which is indispensable when re-equipping the GAZ-3309 brake system.

Brake valve GAZ-3309
Brake valve GAZ-3309


  1. Lever body.
  2. Twin lever.
  3. Fixing bolt.
  4. Cam.
  5. Working traction.
  6. Guide.
  7. Rod for trailer section.
  8. Aperture.
  9. Valve seat.
  10. Inlet valve.
  11. Exhaust valve.
  12. Stop switch.
  13. Signal switch.
  14. Aperture.
  15. Stock.
  16. Case.


This element is needed in order to create additional pressure in the circuits of the node. This makes it possible to improve the quality of braking of the machine, while not requiring maximum effort to press the pedal. The principle of operation of the hydraulic vacuum booster is based on the creation of additional pressure in the inlet part of the power unit, which causes a similar action in the shopping center.

When the mechanism breaks down, the quality of braking deteriorates sharply, as a constant flow of air is supplied to the engine intake pipe. This contributes to the depletion of the fuel mixture in the part of the cylinders. For this reason, the car may stall. At the same time, it will be possible to start it only after the repair of the GAZ-3309 (diesel) brake system. The circuit is designed in such a way that with the indicated malfunction, the unburned mixture removes grease and scratches the cylinder mirror.

Repair of the brake system GAZ-3309
Repair of the brake system GAZ-3309

Working principle

After pressing the pedal, the hydro-vacuum action amplifier picks up this maneuver, multiplying the force many times, forwarding it to the main TC of the vehicle. On the working circuits, piston elements increase the fluid pressure in accordance with the force of the pedal. At the same time, the pressure force increases sharply, the working cylinders of the wheels displace the pads in the drums of the vehicle.

If the pedal continues to move, the force increases further, after which the mechanisms are fully brought into working condition. The pads, entering into engagement with the drum elements, slow down the rotation of the wheels with maximum effort where the wheel comes into contact with the road. The braking force counteracts the rotational counterpart, causing the car to slow down.

To resume movement, the driver takes his foot off the pedal, after which the return spring mechanism returns it to a free position. Following this element, the TC pistons are released. The pads move away from the surface under the force of special springs. Excess lubricant is squeezed out through the open heads, fed into the expansion tank. At the same time, the pressure indicator is reduced to a minimum.

How to bleed the brakes on a GAZ-3309?

Bleeding the system is as follows:

  1. Clean the bypass valves on the wheel cylinders well.
  2. Unscrew the filling cap of the HZ reservoir (master cylinder).
  3. Fill the reservoir with brake fluid. It is necessary to fill in the composition provided for in the instruction manual.
  4. The pressure in the air cylinders should be 0.6-0.8 MPa.
  5. Bleed the front wheel hydraulic circuit.
  6. Remove the cover of the right front brake relief valve, put on the rubber hose, lower its free end into the brake fluid previously poured into a glass container.
  7. Unscrew the bypass valve half a turn, depress the brake pedal several times. The hydraulic drive is pumped until the bubbles stop appearing in the vessel where the rubber hose is lowered.
  8. Tighten the bypass valve with the pedal depressed.
  9. The TC of the left front wheel is pumped in the same way.
  10. Do the operation with the rear drive elements in the same way.
  11. Pumping is performed in the above sequence.
  12. Add brake fluid to the HC reservoir. The level should be 1-2 centimeters below the maximum pointer on the neck of the tank.

Performing the indicated operation, it is necessary to add the working fluid, preventing the tank bottom from drying out.

Repair of brakes GAZ-3309 (diesel)
Repair of brakes GAZ-3309 (diesel)


Preventive maintenance measures for the brake system include periodic inspection of joints and seals for bleeding, secure fastening, and general condition of the assembly. To avoid frequent repairs of the GAZ-3309 brakes, you should regularly change the air dryer cartridge. In addition, in winter, you need to monitor the drainage of condensate, preventing it from freezing. You also need to pay attention to the tightnesscrane cover to the body and its condition. The tightness of the mechanism is checked using a soapy composition.