Hydraulic pump technology is undergoing its definitive change undergoing its definitive change

End of time-honoured hydraulic foot pump with linear air motor is near.
Never before have these three important product characteristics (high delivery,
accurately controllable and ergonomic) been combined in one hydraulic pump.

Despite the advantages of mobility and ease of use, current conventional hydraulic foot pumps have a number of real limitations. For example, these pumps are fitted with an inclined pedal, and the user has to lift his foot fully to operate them. This has the ergonomic disadvantage that the whole body weight rests on one leg, which is tiring and unstable. Moreover, the small hydraulic delivery means that it takes quite a long time before the cylinder is fully extended and the maximum operating pressure is reached. For example, it takes on average more than 20 seconds to let a 10-ton cylinder with a stroke length of 152mm fully extend and then build up to 700bar operating pressure.

Another typical disadvantage of air/hydraulic pumps is the poor controllability. This is simply because the maximum pump delivery is reached as soon as the pedal is depressed. After all, the minimum oil delivery per pump stroke is determined by a single stroke of the linear air motor; fractions are not possible. Reversely, the oil is pressed back unhindered into the reservoir by the fast-working release valve and the spring force of the cylinder. Here also, the return flow cannot be accurately controlled. These limitations are especially important with car repair companies, for example, where accurate metering of the oil flow and thus the cylinder movement is a requirement.

Furthermore, the efficiency of the pump is fairly low, namely approx. 5 percent. Additionally, this is a physical limitationcaused by the ratio between the diameter of the air piston and the hydraulic piston, as well as by the efficiency of the internal air control technology.

Finally, most conventional air/hydraulic pumps have an open oil reservoir with vent screw. This gives a risk that oil will run out of the reservoir if it tilts or falls over. The pump must therefore always be horizontal. An open oil reservoir naturally also leads to internal pollution (from dust and fluids etc.) which can cause the hydraulic system to fail. These are however technical limitations with which the industry has learned to live, partly as a result of the favourable price compared to the more expensive electric pumps.

To tackle these limitations optimally, Enerpac has developed a whole new technology. As a result of the interviews with end-users, the design was based on the following three main objectives: ergonomically better product, optimum controllability of the oil flow, or fine metering and higher oil flow. Additionally, to prevent possible leakage with tilting and to prevent internal pollution, a closed oil reservoir was assumed, as well as a slightly larger base area for the stability of the pump. The development has resulted in a pump with not only a totally different appearance, but also with a totally different technology 'under the cover'.

With the XVARI Technology, Enerpac has again set a new industrial standard for the 50-year old technology of conventional air-driven hydraulic foot pumps. This technology replaces the popular and widely-used linear air motor technology and, besides strongly improved ergonomics and a more accurate metering of the hydraulic oil flow, also offers a higher delivery and higher efficiency. The popular air-driven foot-operated hydraulic pump is undoubtedly one of the most used industrial pumps for working with high-pressure hydraulics.

We find them in such places as machine factories, production companies, mechanical workshops, maintenance companies and car repair companies. The pumps are mainly used to drive small single- acting (spring return) cylinders and other hydraulic tools. The technology was developed by Enerpac at the end of the 1950s, and Enerpac was therefore the first manufacturer to introduce hydraulic foot pumps based on this technology worldwide. In the following decennia, Enerpac and numerous competitors have admittedly brought various new generations of this type of pump on to the market. However, the technological principle has in fact remained unchanged in the past 50 years. These air-driven hydraulic pumps have an average hydraulic delivery of 0.16 litres/minute with a pressure of 700 bar. The principle is simple: the pump is driven with (workshop) compressed air from 5 to 8 bar and a linear air motor (pneumatic cylinder) in the pump operates a small hydraulic piston, with which the oil is fed from the reservoir, and the hydraulic pressure is built up. The pump unit is small and therefore has the important advantage that it is easy to move.

Admittedly, the new pump has the same functions as the conventional air/hydraulic pump technology, but offers the user several unique advantages. For example, with the ergonomic design an important advantage has been achieved with respect to the conventional models. Furthermore, an optimally controllable oil flow is possible for the first time, so that the cylinder movement can be controlled more accurately, both during advance and retraction. And thirdly, with the higher hydraulic delivery, the operator can work considerably faster. In brief, the new pump means the end of the more than 50 years hegemony of the time-honoured hydraulic pumps with linear air motors.