Hydraulic Motors Indispensable For A Long Time

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-06-01 01:49

It's all a question of space: Off-road vehicles used in construction, agriculture, forestry, conveyor technology or special vehicles are work machines that require power from limited installation space. Electrification is advancing in this area, but it can only replace a limited number of hydraulic drives that do not require the highest forces. These are primarily power take-offs.

Picture gallery

A purely electrical drive technology in work machines would require powerful high-voltage technology. This is the exception for mobile machines, especially since there is still no broad service structure for such high-voltage technology.

Hydraulics remain indispensable

The high power density of the hydraulics and their compact dimensions will make the hydraulic motor indispensable for mobile machines in the future. They deliver high performance in continuous operation - without an external cooling circuit. In spite of adverse environmental conditions such as water, dust, mud or vibrations, they work reliably with high availability. And they save resources.

Electric drives, on the other hand, offer good controllability and high efficiency. They are quiet and have low torque pulsations.

Knowledge is a competitive advantage

Stay up to date: With our newsletter, the editors of the construction practice informs you every Tuesday and Friday on topics, news and trends from the industry.

Subscribe now!

This results in some homework for developers of hydraulic motors in order to remain competitive. Hydrostatic traction drives on construction sites are noticeably uncomfortable due to their noise level, and the more so, the quieter the other units of mobile machines become. Work must also be done on efficiency, because electric motors also score points here. In addition, hydraulic drives achieve their best values in a small operating field. At high power, the domain of hydraulics, the efficiency usually drops and the highest power loss arises.

Drives that have to start under high torque are problematic, breakaway effects lead to lower starting efficiency. Applications that require slow and steady work movements require larger motors than necessary. Additional measures reduce the symptoms of breakaway effects, but lead to more effort and thus higher costs.

Balance internal forces

Common hydraulic motors are usually built with seven or nine pistons. This results in torque pulsations and uneven work movements at low speed and high torque. Crane booms and other components start to vibrate. Despite decades of development and a high degree of maturity, disadvantages cannot be solved satisfactorily.

Bucher therefore broke new ground in the development of the AX motors: The internal forces of the AX motors balance each other out by means of two opposite rotating piston units that are equipped with twelve pistons. This increases the power density and limits the axial forces, for which a light bearing is sufficient.

Valve

New leak-free lowering brake valves for mobile machines

The internal balance of forces ensures a low noise level. At 350 bar working pressure, it is around

1500 min ^-1 64 dB (A).

The AX engine's 24 pistons eliminate pulsations at low engine speeds. The lower friction of the design principle roughly halves the power loss, and thus also the heat input into the oil circuit and the flushing system.

According to Bucher, the overall efficiency of the AX motors is between 92% and 94%. The start-up efficiency is 99%. There is no breakaway effect under maximum load. Another advantage: Since the hydraulic motors no longer have to be designed for poor starting efficiency, the absorption volume can be reduced accordingly.

AX motors reach their operating speed with less volume flow. Depending on the requirements, the motors can be operated with higher or lower drive power.