The structure of aerial work platforms may vary, but the basic composition is similar. Typically, aerial work platforms consist of the chassis, power take-off device, working mechanism, mechanical structure, and control system. Each system is further made up of multiple components.

Chassis

The chassis is one of the key components of an aerial work vehicle, typically utilizing a commercial truck chassis. It enables the rapid relocation function of the aerial work vehicle and simultaneously provides the source power for the elevated work operations.

Power Take-off Device

The power take-off (PTO) is an essential component of an aerial work vehicle, functioning to extract power from the vehicle's undercarriage and supply it as a power source to the modified parts. Aerial work vehicles typically use a transmission PTO, where the PTO is mounted on a dedicated PTO gear within the undercarriage transmission. As the gear operates, it engages with the corresponding output sprocket inside the transmission, thus extracting power. When the modified parts are not in use, the PTO gear should disengage from the transmission output gear to avoid unnecessary power consumption. The mechanism that drives the engagement or disengagement of the PTO gear is known as the PTO control mechanism. PTO control includes pneumatic and mechanical operations. Other power-taking methods include engine flywheel PTO and transfer case PTO. The PTO converts power into hydraulic power by connecting through a drive shaft or directly to a hydraulic pump.

Return Mechanism

The upward part of the aerial vehicle, relative to the downward part, undergoes a rotational motion known as rotation. The mechanism designed to achieve this rotation is referred to as the rotation mechanism. The rotation mechanism consists of a hydraulic motor, a variable speed reducer, a rotation bearing, a central rotation joint, and a turntable. The hydraulic motor rotates due to pressure oil supplied from a hydraulic pump, driving a reducer. The reducer reduces the speed of the hydraulic motor and outputs torque to the small gear. The small gear drives a large gear on the rotation bearing, which is integrated with the downward part. This causes the turntable to rotate. The central joint's function is to transmit hydraulic power and electrical control signals, preventing the entanglement of hydraulic lines and wires.

Variable speed drive

The telescoping mechanism is a device that adjusts the distance between the elevated working platform and the rotating center. It is primarily composed of a telescoping hydraulic cylinder and its connecting rod mechanism. For telescopic boom models, the telescoping hydraulic cylinders are connected at both ends to the turntable and the basic telescopic arm. For folding and hybrid arm models, the telescoping hydraulic cylinders at both ends are connected to the turntable and the basic arm, respectively, while the upper telescoping hydraulic cylinders are connected to the lower and upper arms, respectively. The telescoping of the hydraulic cylinder is powered by hydraulic oil, which enables the pitching of the boom structure, thereby altering the working range of the platform.

Tensioning Mechanism

The telescopic mechanism is designed to achieve the required boom length by telescoping the arm. It typically includes telescopic cylinders, telescopic booms, telescopic chains (or cables), with the cylinder body and rod of the telescopic cylinder respectively connected to the base arm and the second arm of the telescopic boom. The third arm is connected to the base arm through a chain wrapped around a pulley fixed on the second arm, forming a movable pulley block. The fourth arm is connected to the second arm through a chain wrapped around a pulley fixed on the third arm, forming another movable pulley block. As the telescopic cylinder extends or retracts under the power of pressurized oil, the second arm extends or retracts, driving the first movable pulley block to extend or retract the third arm, followed by the second movable pulley block to extend or retract the fourth arm, thereby achieving synchronous telescoping of the boom.

Leveling Mechanism

The leveling mechanism ensures that the platform remains level during the work arm's range of motion, providing a stable standing surface for the operators. Aerial work platforms typically employ one of the following three balancing methods: mechanical leveling, hydraulic leveling, and electro-hydraulic leveling.

Lifting Mechanism

Some telescopic arm models are equipped with a lifting mechanism for heavy lifting. Typically, this includes a winch, a hook, and a telescopic lifting arm.

Winch: Also known as a hoist reducer or hydraulic winch, a winch is driven by a hydraulic motor, with multiple layers of steel wire rope wound around its outer circumference, and it delivers traction force through the wire rope. Key performance parameters of a winch include single rope tensile force, rope capacity, braking torque, etc.

Hook: Used for lifting objects.

The telescopic lifting arm: Generally, a telescopic lifting arm is set inside the lower arm to increase the lifting height, but the load-bearing capacity of the lifting decreases accordingly.

Subframe

The subframe securely connects the upper working device to the chassis during travel, and during high-altitude operations, it transfers all the load generated by the upper working device through the leg structure to the ground. Therefore, the subframe should possess sufficient strength and rigidity to ensure a firm connection during travel and a stable foundation during operations. There are two structural forms for the subframe: one is a closed box structure, and the other is a double longitudinal beam similar to the automotive chassis beam, utilizing two channel steels as the longitudinal beams, connected by crossbeams between the two longitudinal beams.

Leg structure

The subframe securely connects the upper working device to the chassis during travel, and during high-altitude operations, it transmits all the load generated by the upper working device through the leg structure to the ground. Therefore, the subframe should possess sufficient strength and rigidity to ensure a firm connection during travel and a stable foundation during operations. The subframe comes in two structural forms: one is a closed box-type structure, and the other is a double longitudinal beam form similar to the automotive chassis beam, utilizing two channel steels as the longitudinal beams, connected by crossbeams between the two longitudinal beams.

Turntable Structure

The turntable assembly is fixed on the rotary bearing, rotating with the arm frame structure driven by the rotary mechanism.

Platform Structure

The work platform, also known as a bucket or basket, is a device on the work vehicle that carries workers and equipment in the air. To ensure the safety of the workers, the height of the guardrail on the basket must be at least 1m, the width not less than 450mm, the internal area not less than 0.36m², and the door width not less than 400mm. The bottom plate of the basket should be a non-slip surface.

Barricade

Storage for tools and equipment, as well as for vehicle protection.

Hydraulic System

The hydraulic system of the aerial work vehicle mainly includes: the power system, the interlock system for boarding and alighting, the control system for the undercarriage support legs, and the control system for boarding.

Electrical System

The electrical control system primarily achieves the lifting of the work platform to a designated position by controlling the flow and direction of hydraulic valves; it also includes auxiliary functions such as lighting, communication, and safety position detection.