How to Put a Disc on a Hunter Trimmer

How to Put a Disc on a Hunter Trimmer

The UAZ Loaf brake system includes a working system and a parking system. In turn, the working brake system includes drum-type brake mechanisms on each wheel, as well as a hydraulic drive. The parking brake system at the UAZ Loaf works on a transmission and is equipped with a mechanical drive.

Uaz brake system: device features

With the replacement of some parts, you can pull, but the repair by the brake system is urgent. The life of passengers, the driver, pedestrians and the safety of other vehicles depend on the state of the brakes.

The brake system UAZ “loaf” is:

  • Hydraulic drive;
  • Service brake;
  • Hand brake.

The service brake consists of two pads of the same size. Each block contacts the ends with the pistons of the cylinders, and itself stands on the supporting finger. There are two openings on the wheel cylinders. One is for venting while pumping the brakes. For tightness, a valve is installed in it. The second hole is designed to output brake fluid from the drives. Pipelines connect the cylinders to the entire brake master cylinder system and the brake pedal.

If the UAZ “loaf” compares the front brake circuit and the rear brake circuit, then it is easy to understand that they are the same, with one exception. The rear brake pads work from one cylinder, and the front ones from two. This is because the front axle requires a more efficient brake system due to the greater load during braking.

The mechanism of the drum brake “loaf”

The UAZ 469 brake system, like the UAZ 452, is drum. The drums consist of a stamped steel disc, a cast iron rim and an amplifier welded to the disc. At UAZ “loaf” drums are installed so that they are easy enough to reach and, if necessary, remove to put new ones. To do this, you do not have to remove the hubs, therefore, the operation of the wheel bearings will not be affected.

The drums are attached to the hubs with three screws. The location of these screws makes it possible to install new drums in their original position.

Pumping brakes UAZ 469

The purpose of the pumping manipulation is to remove the air contained in the internal parts of the braking mechanism. Periodically, once a week, inspect the car for damage and leaks, pay attention to:

  • The presence of mechanical damage to the pipes;
  • Violation of seals in the joints;
  • Compliance with the amount of working fluid required norm;
  • The operation of the foot brake lever.

Uaz braking mechanism (469, 452):

A sign that it is time to perform pumping manipulations, an increased working stroke of the foot brake lever, as well as identifying dips when pressing the foot brake. In addition, the lubricant is changed after repair, or a change of components, parts of mechanisms. Regardless of the circumstances, the DOT-4 brake concentrate should be poured and the brakes must be pumped to UAZ 469 and 452 once every two years.

Parking brake system of UAZ cars

Parking mechanism diagram

Fig. 2 Parking brake system: a. View with a brake drum; b. View without brake drum; 1. Adjustment fork; 2. A lock-nut; 3. Drive traction; 4. Expandable cracker; 5. A stub; 6. Drive lever; 7. Adjustment screw; 8. Pad support; 9. Pusher expanding unit; 10. Body of balls; 11. The housing of the expanding unit; 12. Brake drum; 13. The first block; 14. A coupling spring of blocks; 15. Cap; 16. Ball expanding unit; 17. A bolt; 18. The second block; 19. A brake board; 20. Housing adjustment mechanism; 21. A core; 22. Spring; 23. A cup of spring.

The principle of operation of the parking mechanism

The brake of the parking system is equipped on the transfer case and brakes the rear propeller shaft of the Loaf. Its design includes a support disk, with two pads mounted on it, connected by springs. The pads act on the brake drum, which is fixed on the centering belt of the flange of the driveshaft. To the top of the supporting disc is attached the housing of the expanding unit with pushers that are attached to the upper part of the blocks. Inside the pushers are equipped with recesses filled with balls that are in the stock. At the bottom of the support disk is the housing of the adjustment element. In the recesses of the body are placed the support blocks, which are able to move due to the work of a cracker and an adjusting screw.

The brake actuator includes a lever mounted on the support disk and supports the rod of the expanding element balls. The free end of the lever is attached to the fork, which in turn is attached to the rod using a lock nut. The drive rod is attached to the parking brake lever, which is installed in the cab.

In addition, at the UAZ Bukhanka, the parking brake system drive is supplemented with an extension located between the parking brake lever and the brake mechanism. Such an extension cord is a steel cable with its fastening elements.

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Bleeding, sequence

Before pumping the brakes on the UAZ, look for a dry, flat surface. In addition, you need an assistant, since it is difficult to perform the operation alone, but in case of urgent need it is possible.

The sequence of the process is as follows:

  • Remove valve plaque;
  • We monitor for leaks and leaks in the joints and tubes;
  • We monitor the amount of working fluid in the tank for compliance with the norm. If necessary, add to the desired label “MAX”. We carry out manipulations, constantly check and bring the liquid to the desired level, it is impossible that the mixture drops to the “MIN” mark.
  • We swing the foot brake lever without starting the power plant;
  • Dismantle the safety cap from the cylinder bypass valve located at the rear (right), mount the light-transmitting tube, product size 400mm. We wet the empty edge of the tube in a container containing half a liter of working suspension, leave the tube there;
  • Push the stop foot lever 4-5 times until it stops;
  • Holding the lever leg, we unscrew (key 11), pumping valve, make ½, ¾ turn;
  • We control the movement of air masses in the form of bubbles from the cavity of the tube lowered into the suspension;
  • When the stop lever goes all the way down, close the bleeding valve, and squeeze the mechanism;
  • We carry out the actions in the necessary order as much as is necessary for the complete removal of bubbles;
  • We remove the tube, mount the safety cap;
  • In the same way we pump the stop cylinder located at the rear (left);
  • After, we perform similar actions on the pressure regulator.

Cylinders in front on wheels are pumped in the same way, the sequence of manipulations: the right bottom, right top, left bottom, left top. It is necessary to observe the order of pumping. Otherwise, a situation is possible when the brakes on the UAZ loaf are not pumped. If there is no technical wear and smudges, then the problem lies in the violation of the procedure.

When the actions taken have not yielded results and air is also present in the mechanism, then when the force is applied, the stop lever will be elastic to the touch. In this situation, the process is repeated again until a feeling of hard leverage appears.

Air brake control:

When the process is finished, and the liquid continues to bubble, check the seals of the joints, pipes, cylinders (main and working). They control threaded tightenings, change gaskets, gaskets, rings, cylinder sleeves. As for the replacement of the working cylinders, the replacement process takes place in a complex.

At the end of the operation, add the brake fluid to the “MAX” mark, fix the tank plug with a meter that controls the level decrease. The fluid is changed until the new, bright consistency does not replace the old, dark matter.

Replacement brake fluid

Not all car owners know that brake fluid needs to be replaced every two years in a moderate mode. The main mistake often is that many simply add lubricant to the required level, rather than completely changing it.

Uaz Loaf As One to pump the brakes

Like alone bleed the brakes

Before this, you need to unscrew the nozzle of the cylinder or caliper a little so that the liquid flows out by gravity a little.

Every 60 thousand kilometers is required to replace the brake fluid. Car brake fluid can withstand very severe loads. With intense driving and sudden stops, the temperature range can range from 170 to 2000 ° C. It needs to be changed completely because in the process of movement water enters the liquid and dilutes it. A lower concentration negatively affects the quality of the substance. Excessively diluted liquid during boiling can block the brakes with steam and in the future lead to an emergency.

Nowadays, automobile companies have developed a special device that determines the boiling point of brake fluid. The device diagnoses the substance and displays the relevant recommendations. He can show the state of the liquid at the moment and how much its necessary replacement is necessary. The entire procedure takes no more than a minute, but this frees the car owners from unnecessary trouble.

Uaz loaf Like one to pump the brakes

Working brake system UAZ Loaf

Scheme of the working brake system

To learn how the UAZ braking system is arranged, the Loaf scheme allows you to more clearly.

Fig. 1 Scheme of the working brake system UAZ Loaf: 1. Brake disc; 2. A bracket of the brake mechanism of the wheels in front; 3. Contour of the front; 4. The main brake cylinder; 5. A tank equipped with a brake fluid motion sensor to an emergency level; 6. Amplifier with vacuum; 7. A pusher; 8. A brake pedal; 9. Light switch during braking; 10. Rear brake pads of the wheels; 11. Rear cylinder braking wheels; 12. Contour of the rear; 13. Rear axle shaft casing; 14. Load spring; 15. Pressure regulator; 16. Cables of the rear; 17. Equalizer; 18. The central cable; 19. The parking brake lever; 20. Signaling device for the movement of brake fluid to an emergency level; 21. A switch of a signaling device of a parking brake; 22. A front brake shoe of wheels.

Hydraulic brake system

The hydraulic drive of the UAZ working brake system since 1985 began to be produced with two separate branches, one of which is stretched to the brakes of the front wheels, and the second stretches to the rear brakes. The design of the drive includes:

  • Brake master cylinder;
  • A brake pedal that is connected to the cylinder through its piston;
  • Wheel cylinders of the brake mechanisms of the wheels, both in the front and rear of the car;
  • Pipelines and hoses that integrate all cylinders;
  • Control pedal and drive power amplifiers.

Pipelines, the inside of the master cylinder, as well as all wheel cylinders, contain brake fluid.

When a brake force regulator and an anti-lock braking system modulator are installed on the UAZ, they are also placed in the hydraulic drive structure.

The principle of operation of the UAZ brake system

When you press the pedal, the brake system is activated in the following sequence:

  1. The piston of the master cylinder moves fluid into pipelines and wheel cylinders;
  2. In wheel cylinders, the brake fluid causes all pistons to move, as a result of which the brake pads approach the drums;
  3. When there is no distance between the pads and drums, the release of fluid from the brake master cylinder will cease;
  4. When you press the pedal more strongly, the fluid pressure rises in the drive and braking of all wheels starts at once.

The greater force applied to the pedal contributes to the greater pressure generated by the piston of the main cylinder on the fluid, as well as the effect of greater force due to all the pistons of the wheel cylinder on the brake pad.

This suggests that the simultaneous operation of all the brakes and the regular relationship between the force on the brake pedal and the drive forces of the brakes is created thanks to the hydraulic drive functioning system.

When the brake pedal is loosened, it returns to its original position due to the functioning of the return spring. In addition, due to the spring, the piston of the brake master cylinder also moves to its original position. And the coupling springs of the mechanisms in turn move the pads from the drums. Brake fluid from the wheel cylinders through the pipelines is pushed into the brake master cylinder.

Advantages and disadvantages of the hydraulic drive

Advantages of hydraulic drive:

  • Quick response provided by impressive rigidity of pipelines;
  • High efficiency, since the waste of energy occurs as a result of transfusion of a low-viscosity fluid from one device to another;
  • Not complicated design;
  • Low weight and dimensions as a result of high drive pressure;
  • Comfortable layout of drive units and pipelines;
  • A chance to achieve the necessary distribution of braking forces among the axles of the car, obtained due to the difference between the diameters of the pistons of the wheel cylinders.

Among the disadvantages of the hydraulic drive can be identified:

  • Needs a special brake fluid with a high boiling point and low thickening temperature;
  • Risk of malfunctions during depressurization as a result of fluid leakage during damage, or malfunctions when filling the drive with air;
  • A strong decrease in efficiency at low temperatures, as a rule, below minus 30 ° С.

Brake fluid

Special brake fluids are sold for use in hydraulic drives. They are produced on alcohol, glycol or oil bases. Mixing them with each other is prohibited, this can lead to a deterioration in their qualities and the appearance of flakes. Brake fluids made from petroleum products may only be used in hydraulic drives whose seals and hoses are made of oil-resistant rubber. This is to prevent the destruction of rubber parts.

The sequence of actions when pumping the brakes UAZ “Loaf”

  • In the corresponding tank, brake fluid, identical to the one previously filled, must be filled to the required level.
  • Cleaning the vent valves. Removing the protective caps and attaching the hose, which with its free end should be lowered into a container filled with brake fluid.
  • Next, you need to sharply press the brake pedal 4-5 times with an interval of 10 seconds, at the same time, after each pressing, the pedal should be released smoothly (for these manipulations you will need an assistant). When the pedal is depressed, the bypass valve is turned with a wrench half a turn and the liquid with bubbles begins to sink into the container. After the air plugs exit, the valve is screwed back. A similar procedure is repeated until the cessation of bubbles and the appearance of “elasticity” in the pedal.
  • After all of the above, the bypass valve closes, the rubber hose is removed, the cap is attached back to its place.

During pumping of the UAZ brake system, fresh brake fluid should be added to the tank, if necessary. The fluid flowing from the hose is not suitable in this form for subsequent use, since it is initially subject to filtration and sedimentation.

It is better to start pumping from the rear right wheel, then go to the rear left, then the front right and, finally, the front left. For vehicles with separate drive, you need a separate bleeding of each part.

If the bubbles do not disappear after a long pumping, check the tightness of the entire system, especially the cylinders. Replace or repair if necessary.