The tractors are equipped with a fifth wheel coupling with a locking hole in the grips with a diameter of 50.8 mm. The device is designed for articulated connection of a tractor with a semi-trailer having a standard kingpin.

Saddle 10 (Fig. 1), on which the semi-trailer rests, oscillates in the longitudinal and transverse planes. In the longitudinal - on the axes 15, in the transverse - due to the deformation of the rubber of the hinges 11.

Ural fifth wheel

The coupling of the saddle with the pivot of the semi-trailer is carried out by two grippers 2 of the coupling mechanism.

The grips are mounted on pins 14 and, rotating on them, cover the kingpin.

The grips are held in the closed position by the locking fist 3 under the action of the spring 5 mounted on the locking fist stem.

When the hitch has occurred, the self-release safety lock 4 is in the vertical position.

To disengage, turn the self-release fuse to the side and use handle 1 to move the locking fist 3 to the extreme forward position.

Latch 6, pulled by spring 7, fixes the fist in the forward position.

When the tractor leaves, the semi-trailer kingpin spreads the clutches of the coupling mechanism and disengages from them.

At the same time, the left grip with the pin on it turns the latch, which allows the locking fist to move back until it stops against the ends of the grips, which are held in the open position.

In this position of the mechanisms, the saddle is prepared for automatic coupling with a semi-trailer.

When hitching, the king pin of the semi-trailer, moving, turns the grips and forces them to close.

The locking fist, sliding along the ends, enters the groove of the grips, closing them automatically.

The fifth wheel coupler is attached to the tractor frame through brackets 13, subframe and bars. To facilitate the coupling of the tractor with the semi-trailer, overrunning skids are installed behind the fifth wheel.


Hitching and uncoupling

Before coupling, make sure that the saddle device and its fastening are in good condition, the saddle and slide rails are not dirty and there are no foreign objects on them, if necessary, clean the upper plane of the saddle from contaminated grease and lubricate with a thin layer of fresh.

Reliably brake the semi-trailer with a parking brake and place it on the support device so that the semi-trailer support plane is at the same level with the tractor saddle or slightly below it from the ground.

Hitch and unhitch on a flat, hard surface.

In this case, the longitudinal axes of the tractor and the semi-trailer must be located in one straight line.

Concatenation order:

  • 1. Move the self-release safety catch aside and put the gripper lock handle in the front end position.
  • 2. Drive the tractor in reverse at low speed to the semi-trailer so that the semi-trailer king pin is between the slide rails and enters the saddle catches to the stop. In this case, the coupling should occur automatically.
  • 3. Apply the parking brake to the tractor.
  • 4. Make sure that the gripper lock handle is in the rear end position, and the self-release safety is lowered vertically and locks the locking shaft.
  • 5. Raise the trailer carrier to its highest position and secure it securely.
  • 6. Connect the connecting cable of the semi-trailer wiring to the socket.
  • 7. Connect the connecting hose of the pneumatic drive of the tractor brakes to the coupling head of the semi-trailer.
  • 8. Open the pneumatic brake valves on the tractor and semi-trailer by placing their handles parallel to the longitudinal axis of the valve.
  • 9. Release the trailer's parking brake.
  • 10. Advance the road train for some distance, make sure the hitch is in good condition, the brakes and the electrical devices of the semi-trailer are working properly.

Uncoupling order:

  • 1. Brake the trailer with the parking brake.
  • 2. Lower the semi-trailer support device until it stops on the road surface, unloading some of the tractor springs.

In case of forced uncoupling on non-compacted ground, place pads under the semi-trailer support device.

  • 3. Close the uncoupling valve of the tractor pneumatic system and the control valve, semi-trailer brakes, placing their handles perpendicular to the longitudinal axis of the valve.
  • Disconnect the air brake coupling heads and close the protective covers of the heads.

Mount the coupling head with the hose on the platform of the tractor.

  • 4. Pull out the plug of the connecting cable of the electrical wiring and the socket and fix the cable on the tie rod platformacha.
  • 5. Push the saddle self-release safety catch aside and move the gripper lock handle to the front end position.
  • 6. Engage first gear and drive the tractor forward at low speed until it is completely disengaged from the semi-trailer.

When installing a fifth wheel on a car, before tightening the bolts and stepladders, it is necessary to provide a gap of 2 - 3 mm between the brackets of the frame and the subframe with shims.

The tightening torque of the saddle device should be 10 - 14 kgf / m, for bolts m14 - 8 ÷ 10 kgf / m.