What are cables? Steel cables, a.k.a. wire ropes for cables over 3/8″ diameter, are a flexible connection mechanism used on a variety of lifting equipment. They are an evolution from chain links which were notorious for catastrophic failure. Unlike chain, steel cables are made from many strands of wires twisted into specific patterns for improved strength and flexibility. Failure of a single strand in the cable is less critical as the other strands can take up the load.
In the automotive repair industry steel cables are most commonly seen on 2 post and 4 post style automotive lifts.
A typical 2 post lift, consists of a high pressure hydraulic cylinder assembled into each tower. When powered up, these cylinders support the weight of the vehicle while the cables are used to balance out any uneven lifting conditions. Even though they don’t support load, they are still performing an important role in keeping the vehicle level on the lift.
Two post lifts typically have small diameter sheaves due to space constraints in their design. Smaller sheaves mean tighter bending radius and higher bending stresses on the wires. So, inspect your wire ropes and sheaves frequently as detailed in your owners manual.
On 4 post lifts, the wire ropes are responsible for supporting the weight of the vehicle and sections of the lift. Hydraulic cylinders pull on the ropes, which in turn pull on the structure of the lift allowing the load to raise. As you can imagine, if a wire rope on your 4 post hoist fails, the load will free-fall “until and if” the mechanical locks catch it. The “if” in that statement depends on the condition of you locking system. Clean, inspect and replace damaged or broken parts of your locking system immediately. Never use a lift with a malfunctioning locking system.
You may think this will never happen to you, but cable failure is actually more common than you think so please inspect your cables frequently and take them out of service when they don’t meet the standards.