QTZ40 Tower Crane

    The QTZ40 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 40 t·m and a lifting capacity of 4 tons, it includes models such as TC4708 and TC4510. The hoisting mechanism employs variable-pole speed control, while the slewing mechanism utilizes variable-frequency speed regulation. 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.

QTZ40 Technical Specifications 

【Hoisting Mechanism】:

     The hoisting mechanism (1565 kg) employs a YZTD200L2-4/8/24 wound-rotor motor. The motor drives the gear reducer via a spline coupling, which in turn drives the drum. This configuration enables three distinct hoisting speeds, ensuring smooth starts and stops with minimal impact. With a 2-rope configuration, speeds reach 70 m/min, 35 m/min, and 10 m/min. A 4-rope configuration achieves 35 m/min, 17.5 m/min, and 5 m/min.

   A normally closed brake is installed at the rear of the motor. A height limiter is mounted on one side of the drum and can be adjusted to the required height. This mechanism achieves ideal lifting speed and controlled lowering of the load. Through variable pole speed control, it offers reliable operation, simple handling, and easy maintenance. Configuration details are as follows:

【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. This tower crane employs two such devices, symmetrically distributed on both sides of the slewing bearing and mounted on the upper support. Their pinion gears mesh with the large ring gear of the slewing bearing. The slewing limiter restricts the tower crane's rotation to 540° in any single direction to prevent cable breakage.

    The slewing motor is connected to the planetary gear reducer via a hydraulic coupling, driving the slewing pinion to mesh with the slewing bearing for transmission. This design features a compact structure, aesthetically pleasing appearance, and reduced slewing impact. Configuration details are as follows:

【Variable-amplitude mechanism】:

      The boom hoist mechanism (240 kg) employs a dual-speed YDEJ112M-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.

     The multi-pole motor connects to a planetary gearset, driving the boom drum for movement. By switching poles, it achieves different boom extension speeds. The gear reducer is housed within the drum, offering a compact structure and aesthetically pleasing appearance. Configuration details are as follows:

【Boom】:
    The boom employs a double-lifting-point spatial truss structure. A trolley luffing mechanism is installed at the root section of the boom, featuring a walkway frame. Each upper chord of the second and fourth boom sections incorporates a tie rod lifting point. All sections are connected via pins. A trolley traction mechanism is mounted on the first boom section, while a wire rope anti-twist device is fitted at the boom tip for convenient installation and maintenance.

【Balancing Arm】:

    The total length of the counterweight boom is 11.02 meters. Using pins, the counterweight boom and its tie rods are integrated with the rotating tower body and tower top. Guardrails and walkways are installed on both sides of the counterweight boom.

【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 bearing connects to the rotating tower body above, while the lower bearing connects to the standard tower sections below.

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【Rotating Tower Body】:

The rotating tower body is an integral frame structure. Its upper surface features guide plates on both sides for mounting the boom and counterweight arm. The top is connected to the tower cap via four pins.

【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 QTZ40 electronic 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.