How high speed hydraulic motors are changing the way conveyors operate
Compact and lightweight, hydraulic direct drive systems are well suited to machines like belt conveyors.
The Hagglunds hydraulic motor mounts directly on the pulley shaft, while the rest of the system can be placed where it fits best, without foundations or alignment issues. Still more important are the operational advantages, many of which extend conveyor lifetime, these include the following:
* Soft starts that help reduce belt stretching and extend belt life
* Perfect process feed rate control through fully variable speed
* Unlimited starts and stops with no risk of overheating
* 100% load sharing that reduces shaft and pulley stresses
* Possibility to drive both head and tail
Hägglunds, a specialist in hydraulic direct drive systems, has supplied a variety of industries with conveyor belt drives. Most have employed the Hägglunds CB hydraulic motor, which was recently renamed Hägglunds Quantum. Today, that motor is joined by the Hägglunds Quantum Power, which shares the original motor’s DNA but also creates new, efficient opportunities.
Efficiency challenges at higher speeds
Until now, hydraulic direct drive systems have been most competitive for specific types of belt conveyors. They have excelled on slow-moving conveyors, typically operating below 50 rpm, or on faster conveyors that start and stop frequently – where electromechanical drive systems are usually overdimensioned to avoid overheating.
Higher speeds require more hydraulic fluid to pass through the motor, which has meant increased pressure and efficiency losses. Thus, on fast-moving conveyors where operations are smooth, electromechanical systems have often had the upper hand.
New design that minimises losses
With the new Hägglunds Quantum Power motor, Hägglunds has changed the equation substantially – not only for belt conveyors but also for other equipment, such as mills, crushers and kilns. Built upon the Hägglunds Quantum concept, the Hägglunds Quantum Power has the same interfaces and small frame sizes as its sister motor, but it features an innovative internal design and a range of other enhancements.
A new connection block, which has eight main ports of 2” in diameter, combines with an optimised distributor and refined internal channels to provide more flow to the radial pistons – with minimal losses, which reduces operating pressure. The result is a hydraulic motor whose efficiency at higher speeds aligns with that of an electromechanical solution, which brings the other advantages of a hydraulic direct drive back into play.
Calculating the efficiency improvement
To exemplify the difference, one can compare motors of equivalent size in a high-power belt conveyor application, requiring 75 kNm of torque while running at 65 rpm. Both the Hägglunds Quantum 400 and the Hägglunds Quantum Power 400 could supply the necessary torque, but their energy consumption at this higher speed would differ significantly.
Over one year of continuous operation, calculated as 8,000 hours (accounting for planned maintenance), the Hägglunds Quantum Power would save around 312 MWh compared with the Hägglunds Quantum. This equates to 138 metric tons of CO2* – or the energy used by 127 electric cars with an annual mileage of 12,000 km.** Looking at it another way, the input energy saved would be roughly 7% of the shaft output in same time frame.
Extended lifetime as well as energy savings
While the Hägglunds Quantum motor remains the appropriate choice for many belt conveyors, the Hägglunds Quantum Power makes a long-lasting hydraulic direct drive system feasible for many more. At higher speeds, its minimised losses and the resulting reduction in operating pressure mean an even longer motor lifetime.
In fact, there are further aspects of the Hägglunds Quantum Power that enhance its lifespan. These include reinforcements, such as a diamond-based piston coating and an improved cam roller design, but also monitoring and service aspects, including a built-in temperature sensor and separate seal retainers that allow easy seal changes from the outside. All these features are standard, as is the motor’s ability to work with Environmentally Friendly Lubricants.
Between higher efficiency, extended motor lifetime and the overall ability of a hydraulic direct drive system to safeguard the belt conveyor it drives, the Hägglunds Quantum Power gives sustainability-conscious mining customers reason to consider a hydraulic solution – even at higher speeds.
* Source: ember-climate.org (calculated at a world average grid carbon intensity of 442 g CO2e per MWh)
** Source: bmuv.de/en/
