When a load is lifted or moved from multiple points, those points need to advance together.
That requirement sounds straightforward. However, in practice, it’s a persistent challenge in heavy load movement—because load distribution is almost never uniform.
Resistance varies across support points. Some cylinders respond more easily than others. Left unaddressed, those differences cause some points to advance faster, the load to move out of level, and stress to accumulate on both the equipment and the structure being moved.
Synchronous power units (SPUs) are designed to remove that variability before it compounds.
This page explains how multi-point systems behave under load, how different hydraulic approaches affect movement, and how synchronous power units keep all points moving together.
What Makes Multi-Point Movement Difficult
When a load is lifted or moved from multiple points, each point does not experience the same conditions.
Load distribution is uneven. Resistance varies. Friction and alignment shift as movement progresses. These differences affect how each cylinder responds—and in a conventional hydraulic system, the results are predictable: oil follows the path of least resistance.
Cylinders under a lighter load advance more easily. Cylinders under heavier load lag behind. The system is behaving exactly as designed. It’s just not maintaining level.
To compensate, operators must continuously monitor movement and make manual adjustments throughout the lift—jacking end-to-end, or manually feathering valves to equalize flow rates. It’s manageable, but it introduces variability that depends on constant attention.
How Synchronous Power Units Change the Equation
A synchronous power unit changes how oil is delivered to the system.
Rather than supplying all circuits from a shared oil source—where flow naturally migrates toward lower resistance—a synchronous power unit divides the system into independent circuits. Each circuit is driven by its own dedicated piston on a common shaft, and each delivers the same volume of oil regardless of what the other circuits are experiencing.
Because these circuits are isolated from one another, a change in resistance at one point does not redirect flow away from the others.
The result: all cylinders advance at closely matched rates, even when load distribution is uneven. And because the pump itself maintains equal flow, operators can raise or lower all points simultaneously using a single master control valve—without needing to track the load’s precise center of gravity or monitor pressure at each individual cylinder.
Conventional vs. Synchronous: How the Systems Compare
The difference comes down to how flow is controlled.In a conventional system, level is maintained through continuous correction. In a synchronous system, it’s maintained through how the system functions.
A Practical Note on Skidding Speed
One aspect of an SPU’s design that often surprises crews: ports can be paired together to substantially increase skidding speeds.
By combining the oil output of each pair of circuits into a single port, the flow rate effectively doubles—which means the load moves faster along the skid track. The tradeoff is that pairing ports halves the number of available push points, so it’s a configuration decision based on the specific demands of the move.
For operations where skidding speed is a constraint, this capability is worth factoring into equipment selection early.
Where Synchronous Power Units are Used
Synchronous power units are used wherever loads are lifted or moved from multiple points, and maintaining level is not optional.
That typically means situations involving:
- Uneven or uncertain load distribution
- Tight structural tolerances
- Long travel distances, where small misalignments compound over time
- Equipment sensitive to deflection or tilt
Synchronous power units are frequently paired with hydraulic jacks for lifting and skidding systems for horizontal movement–particularly in applications that require both.
Using Synchronous Lifting and Skidding Together
In many heavy moves, lifting and skidding are part of the same sequence.
Loads are first raised—either to install the skidding system beneath them or to reach the required elevation—then transferred onto skid tracks for controlled horizontal movement. Synchronous power units support both phases, helping preserve alignment and stability as the load transitions from vertical to horizontal movement.
For more on how this integration works in practice, see How Hydraulic Skidding Systems Behave Under Load.
Why Synchronous Systems Improve Predictability
Without synchronization, uneven movement has to be managed continuously. That increases reliance on operator input and creates more opportunity for misalignment to develop—especially over longer moves or across multiple lift points.
Synchronous power units reduce that dependency by building consistent behavior into the system itself.
The move becomes more predictable. Corrections become less frequent. And the process is less sensitive to variation in load distribution or resistance as conditions change.
