Hooklift manufacturing is a specialized process that requires advanced engineering, strict quality control, and precision production standards. The hooklift is the core system of a demountable truck, determining its overall performance. It allows for loading and unloading with a single vehicle-mounted device. This adaptable system satisfies global client needs and is widely utilized in sanitation, construction, firefighting, transportation, military, and trash recycling industries.

Hooklifts are mainly categorized into four types: small-arm fixed, telescopic, swing arm, and composite. Based on our years of experience, the following are the main process controls in hooklift  manufacturing.

1. Hooklift Manufacturing Basic structure

The hooklift equipment serves as an important component installed on the truck chassis, primarily for loading and unloading the bin body. The system includes a hydraulic lifting device that unloads the bin body from the hooklift subframe and pulls the bin body onto the subframe. Additionally, this hooklift equipment can self-unload the bin body, provided the hydraulic self-unloading lock is locked during the process. The whole system drives the middle frame to overturn through the main cylinder, the telescopic arm cylinder drives the telescopic arm and then drives the hook through the lock hook cylinder to complete the whole process of loading and unloading the bin body. Finally, pull the bin body onto the hooklift along the rear roller using the hook and lock it in place with the hydraulic bin lock. The main structure of the hooklift is displayed as follows.

hooklift overview

2. Installation process and control points of hooklift

2.1 Adjust the chassis level

When starting to modify the chassis, keep the truck’s main beam horizontal and ensure the chassis is free of warping. Confirm the following points first:

  1. Ensure that all wheels are facing forward;
  2. Ensure that the tire pressure is normal;
  3. To lift the bare chassis, use at least two adjustable brackets. Do not remove the brackets during the chassis modification process.

2.2 Install hooklift subframes

If components like gearboxes, crossbeams, and brake boosters on the truck chassis exceed the chassis plane height and interfere with the installation position of the hooklift system parts, adjust the interfering components. You can either remove or add hooklift subframes on the chassis frame to resolve the interference issue.The height of the added hooklift subframes should not exceed 100 mm.

Schematic diagram of adding hooklift subframes

Figure 2: Schematic diagram of adding hooklift subframes

2.3 Connection between hooklift and chassis

2.3.1 Installation of hooklift mounting plates

When placing the hooklift on the chassis main beam, ensure that the contact surface between the hooklift main beam and the chassis’s main beam has no gaps. Arrange fixing plates at load-concentrated positions during the movement of the hooklift. Use plates that are 8-12 mm thick for the fixing plates and choose connecting bolts sized M12-M14. It is recommended that the bolt strength be 10.9 or above.

When drilling holes in the chassis main beam, keep the following points in mind:

  1. Use the existing holes on the main beam as much as possible.
  2. Before drilling, confirm that no damage or impact will occur to any pipelines and wires.
  3. Use a drill bit as close to the bolt diameter as possible for drillin

g, for example, use a 13.9mm drill bit for M14 bolts.

  • Do not drill holes at the edge of the side beams.
  • Do not drill holes at the tapered end of the towing truck chassis frame.
  • Do not weld filler at the holes of the chassis frame.

  • The drilled holes must be primed and top-coated to ensure durability and prevent corrosion. The position of the main beam fixing plate is illustrated in the accompanying diagram.

Position diagram of sill beam fixing plate

Figure 3: Position diagram of sill beam fixing plate

2.3.2 Shorten the front part of the hooklift subframe

Before installing the hooklift on the truck chassis, first shorten the front part of the hooklift subframe to the normal length. This adjustment ensures that the center of the rear roller is positioned 76 mm from the rear end of the chassis main beam. The specified distance from the rear end of the chassis main beam to the center of the hooklift rear roller is detailed in the accompanying diagram. Arrange the front part of the hooklift subframe as forward as possible and shorten it.

The schematic diagram for shortening is illustrated in Figure 5. For vehicles without rear supporting iron wheels, position the hooklift close to the cab to prevent the truck from tilting forward. The distance from the rear axle center to the center of the hooklift rear roller is detailed in Figure 6. In the figure, L is the distance from the rear axle center to the center of the hooklift rear roller. The shorter L is, the less likely the truck is to tilt its head.

shortening the front beam of the auxiliary beam

Figure 5: Shortening the front beam of the auxiliary beam

Distance from the rear axle center to the center of the hooklift rear roller

Figure 6: Distance from the rear axle center to the center of the hooklift rear roller

2.4 Installation of the oil pump and drive shaft

If the truck gearbox has an additional take-off device and there is sufficient space between the drive shaft and the crossbeam, you can adopt the method of installing a direct pump additional device. This setup allows for more efficient integration with the hydraulic system. The key is to ensure that the rotation direction of the oil pump and the connection position of the take-off device and the pump match. Since the oil pump typically rotates counterclockwise, if the directions do not align, disassemble the rear cover and rotate it 180° for compatibility. When using a flange take-off device, do not use an adjustable pump; instead, utilize a drive shaft flange. In this scenario, employ a special bracket to attach the flange hub to the oil pump shaft before installing the pump onto the truck chassis. According to the product instructions, the drive shaft bracket must be securely fixed. An adapter can indeed be installed between the pump and the take-off device to facilitate proper connection and function within the hydraulic system. Since the installation positions of the oil pump and valves are adjustable, use flexible hoses to connect the hydraulic system pipelines.

2.5 Installation of oil tank and oil circuit connection diagram

The hydraulic system of the hooklift is a high-pressure connection system with the highest working pressure of 35 MPa. Connect high-pressure hoses between the hydraulic pump and the main control valve, ensuring these hoses do not vibrate. Additionally, install the hydraulic oil tank as high as possible while ensuring the filter element of the return.  Refuel from here by removing the cover. The working principle of the oil circuit is that the hydraulic pump obtains power from the chassis through the take-off device, pressurizes the hydraulic oil in the oil tank into high-pressure hydraulic oil, and then transmits the pressure to the main control valve body through high-pressure oil pipes. The main control valve controls the stroke of various cylinders on the hooklift to realize the loading and unloading operation of the hooklift. Meanwhile, the returned hydraulic oil flows back to the oil tank through the return oil pipe. Refer to Figure 7 for the oil circuit connection diagram.

2.6 Installation of rear axle support

Rear axle supports include “rear axle support cylinders” and “rear axle support rollers”, which are mainly used to reduce the rear overhang load of the chassis main beam and prevent the truck from tilting its head during hooklift operation.

Oil circuit connection diagram

Figure 7: Oil circuit connection diagram

2.6.1 Rear axle support cylinders

The rear axle support cylinders are suitable for rear axle support forms on softer and harder ground. Pay attention to the following points during installation:

  1. There is 1 rear axle support cylinder on the left and right, installed above the steel plate springs of the last axle of the chassis and as far back as possible;
  2. In the unloaded state, maintain a distance of 30-50 mm between the fully extended cylinder rod of the support cylinders and the steel plate springs.

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    Do not weld the connecting plates of the rear axle support cylinders to the chassis main beam to allow for easy disassembly of the cylinders.

2.6.2 Rear axle support rollers

Rear axle support rollers are ideal for supporting rear axles on harder ground. Pay attention to the following points during installation:

  1. The rear axle support rollers should be as far back as possible;
  2. Usually, when loading and unloading on a horizontal road surface, maintain a ground clearance of 100-150 mm at the lowest point of the rear roller;

  3. The design should ensure that the roller frame matches the chassis width and connects to the chassis using 12 mm thick connection plates and at least 8 M14 bolts.

Conclusion

In the installation of the hooklift, first ensure that the chassis model matches the hooklift; secondly, strictly implement the consistency requirements of the product in the whole special truck modification process.

At VLE, we provide the most reliable hooklift system an affordable price for your business. Discover more with the wide loader range hooklift on our website.

This blog is translated from the article “Control Points of Hooklift in Manufacturing Process of Hooklift Truck” by Qizhong Yao 2011.

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