Daily maintenance and precautions for 50 or 90 traction pin saddle of semi-trailer tractor

1. Maintenance and precautions for newly received vehicles

After receiving the trailer and the main vehicle, carefully check whether there are any bumps, burrs, welding slag, welding nodules and other foreign objects on the surface of the main vehicle saddle and the trailer traction plate. If there are any, clean and grind them in time, otherwise it will cause abnormal wear and tear of the saddle and traction plate in the future.

When adding grease for the first time after cleaning the saddle and traction plate, try to add blue, dark gray, or tan lithium-based grease (lithium-based high-pressure black (brown) grease containing graphite calcium or molybdenum dioxide is recommended).

Lithium-based high-pressure lubricating grease has good viscosity, wear resistance, pressure resistance and stability. It is not recommended to use the yellow ordinary calcium-based grease that has been basically eliminated in the heavy truck field.

Calcium-based grease has good water resistance but poor wear resistance, high temperature resistance and stability. It is easy to hydrate (lose viscosity) and lose its lubricating properties. It is generally used for low-speed, low-temperature components such as water pumps and is basically not used on trucks.

If the main vehicle saddle and trailer towing plate are already coated with grease, it is recommended to clean the grease thoroughly after receiving the vehicle, carefully check the main vehicle saddle and trailer towing plate to ensure that their surfaces are clean and free of foreign matter, and then add lithium-based grease.

2. Precautions for connecting the main vehicle and the trailer

1. When connecting the tractor and the trailer, adjust the height of the trailer legs to ensure that the lower plane of the trailer traction plate is 1-3CM lower than the upper plane of the main vehicle saddle. Too high or too low will cause the main trailer to fail to connect. In serious cases, it will cause the wear ring of the saddle, the lock hook and the surface of the traction plate to be damaged.

2. When the tractor is backing up, try to straighten the tractor to ensure that the center lines of the tractor and the semi-trailer are consistent. Generally, the horizontal offset of the two center lines cannot exceed 4 cm, and the angle between the two center lines is limited to within 5° when fully loaded and within 7° when empty.

3. When separating the tractor and trailer, make sure the ground is flat. If they are separated for a long time, be sure to wedge the trailer wheels to prevent the semi-trailer from slipping. Extend the outriggers until the load is transferred from the tractor to the outriggers. Do not extend the outriggers too long (a gap of 3-5mm between the traction plate and the saddle is sufficient), otherwise the semi-trailer will be lifted off the saddle. Be careful that the saddle will be wedged and cannot be detached.

3. Precautions during use

1. After the tractor and trailer are connected for the first time, the connection status should be checked by driving forward, backward, and in an S-shape. If the clearance between the trailer towing pin and the saddle lock hook is too large (there is an abnormal sound), the clearance needs to be adjusted through the adjustment rod on the side of the saddle to ensure that it is not loose.

2. When a new vehicle is running for the first time for about 1000 km, the saddle, traction plate, and traction pin grease must be thoroughly cleaned and checked (diesel can be used for cleaning) and refilled with grease. After that, the grease must be replaced and checked every 6000-8000 km (it must be thoroughly cleaned when replaced).

3. Every time the vehicle runs about 40,000 km or if there is a loose or impact sound when starting or braking, the adjustment screw on the side of the saddle should be rotated counterclockwise to adjust the gap between the saddle lock hook and the traction pin.

The looseness of the lock hook and the traction pin is something that truck owners tend to overlook. If the looseness is not adjusted in time, it is easy to cause the saddle wear ring, the lock hook to be damaged, and even the traction pin to be worn and damaged. Especially the welded traction pin is more troublesome to replace once it is damaged.

4. The wear condition of the saddle wear ring, lock hook, saddle panel and trailer towing pin should be checked every 40,000 km of vehicle operation. Those with excessive wear should be replaced in time.