How to judge the overall condition of a used tower crane when buying one

When you buy a used tower crane, you can judge its overall condition from the mechanical parts, structural parts, electrical system, appearance, etc. The following are the specific methods:

Mechanical parts inspection
Power system
Engine: Start the engine and observe whether it starts smoothly, with or without abnormal shaking, noise or black smoke. Check whether the oil temperature and water temperature of the engine are within the normal range, and whether the oil pressure is stable during operation.
Motor: check the appearance of the motor for signs of damage and overheating, listen to its sound when running to see if it is smooth, and check whether the insulation of the motor is good to prevent leakage and other safety hazards.

Transmission system
Transmission: Check whether there is any oil leakage in the transmission, whether the gearshift is smooth during operation, and whether there is any abnormal sound such as stagnation and tooth beating. By observing the color and texture of the transmission oil, determine whether the oil quality is good and whether it needs to be replaced.
Transmission shaft and coupling: check whether the transmission shaft is deformed and worn, whether the connection is firm, whether the coupling is loose and cracked, and whether there is any jumping or abnormal vibration during operation.

Brake system
Brake: check the wear of brake pads, generally speaking, the thickness of brake pads should not be less than 1/3 of the original thickness. test the braking effect of the brake, brake test under no load and rated load to ensure that the braking distance is within the prescribed range, reliable braking, no slipping phenomenon.
Brake fluid: check whether the brake fluid level is within the normal range, check whether the brake fluid is turbid and deteriorated, if there is any problem, it should be replaced in time so as not to affect the braking performance.

Lifting mechanism
Wire rope: Observe the degree of wear and tear of the wire rope, wire breakage, and check the lubrication condition of the wire rope. If the wear of wire rope exceeds the specified limit or the number of broken wires reaches the standard of scrap, it should be required to be replaced.
Reel and pulley: check the surface wear of reel and pulley, whether there are cracks and deformation, whether the rotation is flexible or not, and the depth of wear of the groove bottom of the pulley should not exceed the specified value.

Structural components inspection
Tower body: carefully check whether the connecting bolts of the standard section of the tower body are tightened, and whether there is any loosening or missing phenomenon. Check the surface of the tower body for obvious deformation and cracks, especially at the welds and stress concentration areas, which can be detected by using a magnifying glass or a flaw detector.
Lifting arm: Observe whether the shape of the lifting arm is straight, with or without bending and twisting deformation. Check whether there are cracks and de-welding in the chord and web of the lifting arm, and focus on whether the connection parts of the root and head of the lifting arm are firm.
Counterbalance arm: check whether the structure of the counterbalance arm is complete, without deformation, damage, whether the counterweight on the counterbalance arm is complete, fixed and reliable, the number and weight of the counterweight should be in line with the design requirements of the crane.
Slewing bearing: check whether the gear ring of the slewing bearing is worn, whether it is smooth when rotating, and whether there is any stagnation and abnormal sound. Check whether the connecting bolts of the slewing bearing are loose, whether the seal is good, and whether there is oil leakage.

Electrical system check
Electrical components: Check the contactors, relays, circuit breakers and other electrical components in the control cabinet to see if there is any corrosion or damage to their appearance and whether they are sensitive and reliable. Check whether the wiring of each electrical component is firm, loose, aging, broken phenomenon.
Wires and cables: check the wire and cable jacket for damage, aging, cracking, internal wires for breakage, short-circuit. Check whether the laying of the cable is neat, reasonable, there is no extrusion, wear and tear.
Safety devices: check whether the lifting capacity limiter, lifting torque limiter, height limiter, amplitude limiter and other safety devices are complete and effective, and carry out functional tests to ensure that the specified limit position can be accurately acted on to cut off the corresponding circuits to prevent the crane from overloading, overloading, and other dangerous situations.

Other inspections
Appearance inspection: Observe the appearance of the crane as a whole to see whether the paint is peeling off, rust and corrosion is serious, if there is a large area of rust and corrosion, it may affect the structural strength. Check whether the signs and labels on the equipment are clear and complete, and understand the basic parameters and technical performance of the crane.
Information and documents check: Ask the seller to provide the original factory information of the crane, such as certificate of conformity, quality inspection report, instruction manual, etc., to understand the manufacturer of the crane, production date, technical parameters and other information. At the same time, check the maintenance records of the equipment to understand the maintenance of the equipment and the history of failure records, to determine whether the use and maintenance of the equipment is standardized.