By Josh Cosford, Contributing Editor
When someone mentions a high-pressure hydraulic pump, the vane pump is not likely to come to mind. Vane pumps are often limited to 2,000 psi or less because of the physical limitations of their inherent design. Vanes must reciprocate inside slots while pushing on the cam ring, and when fully extended at high pressure, the vanes are subject to excessive side load.
At high pressure, most vane pumps are prone to high leakage and rapid wear, which is why it’s rare to find a vane pump running more than 3,000 psi. Heat generation is high when vane pumps explore the pressure extremes, and hot metal wears and fatigues more quickly. Plus, many designers prefer the quiet and respectfully efficient performance of these pumps, so why push their limits only to perform and sound like a gear pump?
Nevertheless, manufacturers pushed the boundaries of vane pump design, and you won’t be surprised to learn that the legendary Vickers Inc. was the outfit to develop the high-pressure vane pump decades ago. Their original V-Series vane pump is perhaps the most famous of such pump designs and is still on sale today. In fact, they’re still so popular that dozens of brands manufacture their own version, designed to directly replace the Vickers.
In the 1980s, with continued development and the growth of high-force manufacturing systems (e.g., metal forming, die casting), there was increasing demand for quieter, more compact pumps that could also handle piston pump-level pressures. Their VQ pump offered up a new design with improved materials and balancing, enabling it to reliably output 3,000 psi working pressure.
Vickers engineers pushed their VQ design envelope further by upgrading materials, balancing geometry, and optimizing vane loading, giving birth to the HVQ (High-pressure Vane Q series). The resulting pump when released in the 1990s was an absolutely stratospheric rating of 5,800 psi (400 bar). So much of the pump had to be changed, and the HVQ does not directly interchange with the V- or VQ-series pumps.
When Eaton purchased Vickers in 1999, they continued to develop the HVQ pump, making it ideal for segments such as heavy-duty presses, die-casting machines, and steel industry equipment. Unfortunately, Danfoss no longer manufactures the HVQ, which is not to be confused with the still-in-production VQH, itself impressively rated for 3,500 psi.
The VQH is more of an evolution to the VQ-Series pump instead of a direct sibling of the HVQ, but its enhanced rotor design and ductile iron construction have resulted in the industry standard fixed displacement vane pump. These are still used widely on mobile hydraulic machines such as garbage trucks and wheeled loaders.
However, just as with the highly copied V-Series pumps, there are some respected manufacturers offering the HVQ clone and its 5,800 psi rating. Sure, you could also select something more common, like a bent-axis piston pump, but you’d lose the smooth, quiet output even these high-pressure vane pumps are known for. And although not cheap compared to more basic vane pump designs, you can expect vastly less investment than with any piston pump option.
