When lifting a commercial truck, tractor or trailer, it is essential to understand the proper way to jack and lift these types of vehicles. There are two types of lifting devices commonly used for commercial vehicles: hydraulic jacks and air-over-hydraulic jacks.
Hydraulic jacks, usually referred to as bottle jacks, are very portable and come in various heights to accommodate almost every type of vehicle.
When they are used to support a load for a period of time, excessive stress is placed on the seal at the bottom of the cylinder. Since the seal itself is supporting all the weight, when it fails, the load will crash to the ground instantly.
Air-over-hydraulic jacks require compressed air and typically are housed in a wheeled carriage to make them easier to move. They generally have different height adapters to accommodate both tractors and trailers.
JACK BEST PRACTICES
- No matter what type of jack is used, technicians should be sure the lifting capacity of the jack is greater than the weight of the axle being lifted. Note that both types of jacks are designed to lift vehicles and are not designed to support a load by themselves.
- The jack should be inspected thoroughly to ensure there are no oil leaks, particularly around the fill plug and release screw. • The release screw should be tightened and loosened to ensure smooth operation. If the ram has an extender, it and the saddle should be checked for damage.
- Both types of jacks are designed to lift vehicles and are not designed to support a load by themselves. • Jack stands may not be recommended for supporting both ends of a vehicle at the same time
- Never lift both axles of a loaded trailer if it is being supported by the landing gear.
- Oil the extender periodically to ensure the full lifting height of the jack will be maintained. If the jack requires additional oil, use only hydraulic jack oil. Always follow the manufacturer's instructions for replenishing oil or when making any other repairs on jacks and jack stands
- When jacks are not in use, they always should be stored with the ram and the extender fully retracted to prevent any rust or corrosion. Tighten the release valve and store the jack in an upright position where it will not be exposed to water of moisture.