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Hydraulic horsepower can also be a useful comparison measure to determine the capability of a given unit. It is calculated by multiplying the pressure (psi) times the flow (gpm), then dividing by 1,714. "If hydraulic horsepower is not adequate, performance will be poor, as well as detrimental to the skid-steer loader," says Jim Hughes, product marketing manager, Case Construction Equipment.

In addition to losing attachment productivity, using a skid-steer that can't provide the optimum hydraulic system requirements places greater stress on the unit. "Operating a loader at the maximum flow and pressure for long periods of time can result in excessive heat," says Moore.

Hydraulic systems are designed with relief valves to protect them from such abuse. However, Hughes notes, "If your customers are constantly going over relief, they'll be creating heat, which will ultimately damage the hydraulic system and the power train."

Gregg Zupancic, product marketing manager with John Deere Construction, adds, "If the machine has more flow and the attachment does not have the proper flow bypass, heat could be created and potentially cause motor and seal failures. If the machine has less flow than the attachment requires, then the attachment may not run at optimal performance and it can potentially cause unnecessary failures to mechanical or structural parts of the skid steer and attachment."

He continues, "A good example would be a cold planer. If the drum is not spinning at optimal speed, instead of planing the asphalt, it would tend to chuck the surface and cause unnecessary machine bounce or attachment vibration."