QTZ125A Tower Crane

    The QTZ125A tower crane is a reinforced tower crane designed to meet standards such as GB/T50311 “Tower Cranes” and GB5144 “Safety Regulations for Tower Cranes.” It features a rated lifting moment of 125 t·m and a lifting capacity of 8 tons, with models including TC6015, TC5518, TC5022, and TC4526. with a lifting capacity of 8 tons. Available models include TC6015, TC5518, TC5022, and TC4526. 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. This crane supports fixed, traveling, attached, and internal climbing configurations, meeting diverse construction needs for urban mid-to-high-rise buildings, industrial plants, power station dams, bridges, and other structures.

QTZ125A Technical Specifications

【Hoisting Mechanism】:

  The hoisting mechanism (2492 kg) employs a YZRSWF250M2-4/8 wound-rotor motor. The motor drives the reduction gearbox via a splined 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 100 m/min, 50 m/min, and 8.5 m/min. A 4-rope setup achieves 50 m/min, 25 m/min, and 4.25 m/min.

  A normally closed hydraulic push-rod brake (YWZ3H315/90) is installed at the input shaft end of the reduction gearbox (see Figure 4-13). A height limiter is mounted on one side of the drum. This height limiter can be adjusted to the required height, offering reliable control, simple operation, and convenient maintenance.

【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 with a brake at the rear, a planetary gear 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 input end of the reducer is equipped with a normally open disc brake; it can be used for tower crane jacking operations and for braking and positioning the boom during fixed-point operations.

  The slewing limiter is used to restrict the tower crane's rotation to 540° in a single direction, preventing cable breakage.

【Variable-Angle Mechanism】:

   The hoist mechanism (510 kg) employs a YEJ112-4-4kW motor. Driven by a planetary gear reducer, it powers the drum. Through the wire rope, the load trolley achieves three speeds ranging from 0 to 60 m/min, enabling high-speed reciprocating movement along the lifting boom.

  The motor tail features a normally closed brake that provides delayed braking when the trolley motor is de-energized.

    The amplitude limiter prevents misoperation by stopping the trolley before it contacts the buffer at the base of the boom.

【Standard Tower Section】:

 Close-up of the main limb

    Tower sections are available in two specifications based on design strength: reinforced sections and standard sections. Reinforced sections feature walls 2mm thicker than standard sections. These sections are connected using 8-M36 special high-strength bolts. A resting platform is provided every three sections. Standard sections of the same specification are interchangeable.

【Boom】:

   The boom consists of 11 sections, with one tie rod lifting point on the upper chord of the third and eighth sections. Each section is connected by pins. A trolley traction mechanism is installed on the first section, and a wire rope anti-twist device is fitted at the boom tip. The boom length is 60 meters and can be assembled into three lengths—55 meters, 50 meters, and 45 meters—to accommodate varying rotation space requirements. A trolley luffing mechanism is installed on the base section of the boom, featuring a walkway frame for convenient installation and maintenance.

【Balancing Arm】:

   The counterweight arm consists of two sections: one measuring 6.92 meters and the other 6.3 meters, connected by pins. Using these pins, the counterweight arm 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 arm.

【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.

【Rotating Tower Body】:

   The lower section of the rotating tower is connected to the upper support via eight high-strength bolts. The upper section is pinned to the tower top, with the front and rear lug plates connected to the counterweight arm and the lifting arm, respectively. A load limiter is installed on the upper section.

【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.

【Attachment Device】:

Anchoring frame is an anchoring device attached to the side of a building to enhance stability and maintain lifting capacity when a tower crane has reached its free height and requires further upward jacking. It consists of a ring beam and four struts. During installation, the ring beam is tightly fitted against the tower body. Both ends of the struts are hinged to the ring beam and to embedded supports in the building structure. By adjusting the tensioning bolts, the four struts are tightened, securely connecting the tower crane to the building perpendicular to the horizontal plane and maintaining the tower crane's axis perpendicular to the ground.

【Load Limiters】:

【Walking Device】:

   The traveling mechanism features two powered trolleys, each comprising an electric motor, hydraulic coupling, worm gear reducer, disc brake, open gear rim, and travel wheels. The hydraulic coupling ensures smooth starting and braking of the tower crane, with a travel speed of 20 meters per minute.

   The YZ160M2-6-7.5KW AC motor controls the operation of the master controller mechanism. The normally closed disc brake at the tail end of the worm shaft releases during operation and applies delayed braking after shutdown and power disconnection. The delay time is adjustable to ensure a short stopping distance and prevent tower crane sway caused by abrupt braking.

   Two limit switches are installed on the outer side of the active trolley to control the tower crane's travel within predetermined positions, ensuring operational safety.

【Electrical Control System and Safety Devices】:

    This system employs a programmable logic controller for centralized control. The electrical control system utilizes internationally standardized configurations, with low-voltage electrical components sourced from imported equipment. It features a modular assembly design with rail-mounted installation. with rail-mounted installation. Operation is managed through two cross-type master controllers and push-button switches centralized in the driver's cabin, eliminating numerous intermediate relays and time relays required for logic control. Global sourcing employs international products such as OMRON PLCs and Schneider contactors, significantly enhancing overall system reliability while facilitating fault diagnosis, localization, and resolution. Additionally, electrical safety devices like anemometers and obstruction lights are included, along with mechanical safety features such as trolley axle break protection and traction rope break anti-runaway mechanisms.