How Do SPUs Work?
Conventional lifting circuits divide the hydraulic oil flow from the pump into multiple outlets. Since the outlets are all connected to one another, the result is that each outlet will exhibit equal pressure, but not necessarily equal flow. That hydraulic pressure translates into lifting force at the piston of each hydraulic cylinder, and this force is what lifts the load. So for example, when lifting a load which is not equally distributed across all lifting points, the force of gravity acting on each point is not equal: the jacks with greater weight on them will tend to extend more slowly, and jacks with less weight will tend to extend more quickly. If it’s critical that the load remains level at all times, this is a problem.
At the heart of every synchronous power unit is a split-flow hydraulic pump. Unlike conventional hydraulic pumps, a split-flow pump uses its main shaft to drive a number of pistons- one piston for each pressure port. Essentially, each piston in the pump acts like its own miniature pumping unit. Since each circuit is independent, and each piston stroke displaces the same volume, the flow rate coming from each port is equal, and does not vary with changes to the pressure in the line.
Hydra-Pac power units enable you to synchronize your cylinders, and then simply raise and lower all points simultaneously using a single master control valve- no need worry about the load’s precise centre of gravity, or the hydraulic pressure at each cylinder. If the load is unbalanced, you may see different pressure readings on the individual jacking cylinder ports, but this would only become an issue if any of the circuits exceed the maximum pressure rating of the system.