Shock Loading
While minor shock loading may not produce noticeable damage immediately, repeated shock loads can eventually cause a failure. It can damage critical parts of the hoist, particularly those responsible for holding the load.
Under continued misuse, the service life of a hoist will be reduced and in extreme cases the resulting force can destroy the entire hoist.
Signs of damage from shock loading are often indicated by damage to the rope. Therefore, wire rope should be inspected for symptoms of corrosion, loss of metallic cross-section or broken and cut wire strands that have separated resulting from fatigue.
In addition, qualified operators and inspectors should look for shock loading red flags such as a slight downward drift when a load is on the line and the controls are released, potentially indicating component issues.
To inspect for indications of shock loads in planetary hoists before any failures occur, magnetic particle inspection( MPI) of the internal ring and reduction gears and periodic brake tests, should be performed.
Teardown Inspection
Teardown inspections of planetary hoists should be completed according to the usage schedule defined by the manufacturer. When a crane is used for picking up people, a complete teardown inspection is required every three to five years. This includes disassembly, cleaning and inspection and repair or replacement as required of all worn, cracked, corroded or distorted parts such as pins, bearings, shafts, gears, brake rotors, brake plates and the drum and base.
The replacement of key internal components, including the sprag-style brake clutch and pawl if equipped with a ratchet and pawl system, is critical during this inspection to maintain safety and performance.
MPI of the internal ring gear and reduction gears must be performed to aid in detecting cracks in the ring gears due to fatigue. All seals and O-rings should also be replaced during
14 • 515-955-1600 • May 2025