Hydraulic Cylinder with Pump

The “hydraulic cylinder with pump” unit is the smallest hydraulic system. A tank and a check valve are also required as additional components. Once these are combined, however, all necessary components are present to utilize a hydraulic operating principle. Commercially available cylinder-pump units include the following:

• Hydraulic jack
• Pallet truck
• Manual hydraulic press
• Hydraulic engine hoist or transmission jack

Since these devices are operated manually and without the aid of electrical energy, they require additional force amplification. This is provided by particularly long levers. In some cases, these levers are permanently integrated into the system and perform additional functions.

For example, with a pallet truck, the pump lever also serves as the drawbar and steering for the industrial truck. For hydraulic jacks or transmission jacks, the lever is separate and detachable so that it is not in the way when working near the lifting tool.

Necessary additional equipment for manual hydraulic tools

A manual hydraulic jack is an effective tool for lifting very heavy loads, typically vehicles. However, it is not suitable for holding these loads permanently.

Even a small defect or an incorrect opening of the check valve can cause the hydraulic lifting tool to suddenly lose its function. This can quickly lead to very dangerous situations. It is therefore strongly advised to use a hydraulic lifting tool only for its original purpose. Once the load has been raised to the desired height, it should be secured with suitable, form-fitting supports. This relieves the hydraulic lifting device and eliminates any danger in case of failure.

Electric Hydraulic Cylinders with Pump

In manual hydraulic cylinder with pump systems, the pressure generator is designed as a master cylinder. It generates an intermittent stroke, proportional to the immersion depth. In electro-hydraulic systems, radial piston pumps are used. These differ in design and size. Different pumps are used depending on the pressure to be built up. The following hydraulic pumps have proven technically reliable:

• Vane pump
• Gear pump
• Piston pump
• Screw pump

Vane pumps are used for pressures from 70 to 175 bar.

Gear pumps can generate pressures up to 300 bar.

Piston pumps are the most powerful hydraulic pressure generators.
They can generate pressures up to 700 bar.

Screw pumps are rarely used in hydraulics. They are particularly popular in pneumatic applications because they can generate high, constant air pressures.

Weaknesses in Hydraulic Cylinders with Pumps

Demanding hydraulic systems can withstand pressures of over 700 bar. For this pressure to be used safely and purposefully, all components of the system must be appropriately aligned.

This applies particularly to the hydraulic cylinder. Its internal seals are its weak point. They become brittle over time and can then cause a pressure loss. However, such a fault is quickly noticed. With modern sealing materials, the service life can be calculated very accurately. A preventive, interval-based replacement of the low-cost sealing rings makes the hydraulic system reliable, durable, and safe.