QTZ50A Tower Crane

    The QTZ50A tower crane is a reinforced tower crane designed in accordance with the new standard JG/T5037-93 “Classification of Tower Cranes,” meeting standards such as GB/T5031 “Tower Cranes” and GB5144 “Safety Regulations for Tower Cranes”; With a rated lifting moment of 50 t·m and a lifting capacity of 5 tons, it includes models such as TC4808, TC4211, TC3614, and TC3018. The hoisting mechanism employs variable-pole speed control, while the slewing mechanism utilizes variable-frequency speed control. The luffing mechanism incorporates a planetary gear reducer with an integrated drum. The electrical control system utilizes imported components, and safety protection devices are either mechanical or mechatronic products, ensuring comprehensive reliability. Foundations are available in fixed or counterweight configurations. This crane is widely used in various mid-to-high-rise construction projects.

QTZ50A Technical Specifications 

【Hoisting Mechanism】:

     The hoisting mechanism (1000 kg) employs a YZTD200L2-4/8/24 wound-rotor motor. The motor drives the gearbox via a spline coupling, which in turn drives the drum. This configuration enables three distinct hoisting speeds, ensuring smooth start/stop operation with minimal impact. With a 2-rope configuration, speeds reach 58 m/min, 29 m/min, and 8 m/min. A 4-rope setup achieves 29 m/min, 14.5 m/min, and 4 m/min.

【Rotary Mechanism】:

     The slewing mechanism is the transmission device that provides power for the upper slewing of the tower crane. This device consists of a torque motor (equipped with a normally closed brake at the rear), a planetary reducer, a pinion gear, and a slewing limiter. A standard slewing mechanism comprises a wound-rotor motor, hydraulic coupling, electromagnetic brake, planetary gear reducer, pinion gear, and slewing limiter. This tower crane employs such a mechanism mounted on one side of the slewing bearing, installed on the upper support. Its pinion gear meshes with the large ring gear of the slewing bearing.

【Variable-Angle Mechanism】:

      The boom hoist mechanism employs a dual-speed YDEJ112L-4/8 motor. This motor drives the drum via a planetary gear reducer, enabling the load trolley to traverse the boom at three speeds—40 m/min, 20 m/min—through wire rope operation. A disc brake is integrated at the motor tail, providing delayed braking when the trolley motor power is cut off. The boom limit switch prevents misoperation by halting the trolley before it contacts the buffer at the boom base.

【Upper and Lower Supports】:

     The upper support is mounted on the slewing bearing and connected to its inner ring. The lower support is a box-shaped support for the non-rotating section of the crane. Its upper surface is fitted with the outer gear ring of the slewing bearing. The lower support is bolted to the outer ring of the slewing bearing, enabling relative rotational movement between the upper and lower supports via the slewing mechanism. The upper support connects to the rotating tower body above, while the lower support connects to the standard tower sections below.

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【Rotary Limit Switch】:

【Tower Top】

    The top of the tower is a truncated cone, its upper end connected to the lifting arm and counterweight arm via tie rods to maintain the horizontal alignment of both arms, while its lower end is secured with four pins to

    The rotating tower body connection features a work platform and pulley system at the top of the tower to facilitate the installation of the boom tie rods and counterweight boom tie rods.

【Driver's Cab】

   The cab serves as the operator's workstation for controlling the tower crane, fixed to the right side of the rotating tower body. The indicator lights and control handles of the integrated control console are positioned on both sides of the operator's seat, offering convenient operation and a wide field of view.

   The cab electrical control box is located at the rear of the cab, housing the main circuit breaker, lighting circuit breakers, auxiliary circuit breakers, and other devices.

【Load Limiters】:

【Electrical Control System and Safety Devices】 :

      The QTZ50A electric control system employs a state-of-the-art PLC + variable frequency drive (VFD) control approach, significantly enhancing system reliability, operability, stability, and machine efficiency. The incorporation of a VFD enables stepless speed regulation for the slewing mechanism, substantially improving overall equipment stability. This results in markedly enhanced positioning performance and higher operational efficiency.

     The electrical control components of this system are globally sourced from leading manufacturers such as OMRON, Yaskawa, Schneider Electric (TE), and Taiwan's Mingwei. This global procurement strategy significantly reduces the failure rate of the electrical control system, providing effective assurance for enhancing users' production efficiency.  Comprehensive and reliable safety devices are included, such as: lifting height limiters, slewing limiters, and multifunctional limiters for lifting moment, load capacity, and trolley span. Additionally, electrical safety devices like anemometers and obstruction lights, as well as mechanical safety devices such as trolley shaft break protection and traction rope break anti-runaway protection, are incorporated.