Why Your Scissor Dump Isn’t Dumping – And How to Fix It

If you’ve ever loaded your dump trailer or truck bed only to hit the button and hear nothing but a straining pump, you’re not alone. Many users overlook the importance of hydraulic pressure in their scissor hoist system. The reality is, if your system isn’t generating enough PSI, it might struggle to lift heavy loads, especially at the start of the dump cycle when the hoist is at its weakest mechanical advantage.

In this article, we’ll break down why even 200-400 PSI can make or break your lift, how cylinder size and placement affect performance, and why upgrading your hydraulic power unit can solve your dumping problems.

Why Pressure Matters in a Scissor Hoist

Most scissor hoists use a hydraulic cylinder to generate lifting force. The power of that lift comes from hydraulic pressure, which is multiplied by the surface area of the piston inside the cylinder. In simple terms:

Force = Pressure × Piston Area

Why Cylinder Size Matters

Generic hoists often use 5.0” cylinders in their 500 series and 6.0” cylinders in their 600 series. Prime Force hoists are built with 5.5” cylinders in the 500 series and 6.5” cylinders in the 600 series for increased lifting power. The larger cylinder diameters allow higher lifting capacities at the same pressure, ensuring stronger and more reliable dumping performance.

How Relief Valves Affect Dump Performance

One of the most overlooked parts of a hydraulic system is the relief valve. This component is designed to protect your equipment by capping the pressure at a safe limit.

Most industry-standard power units set their relief valves to 3000 PSI. This means that while the pump may briefly spike to 3200 PSI, it will have little to no flow at that rate, meaning your dump bed will not lift under heavy loads.

At Primary Mover, we take a different approach:
✅ Our power units are set to reach and sustain 3200+ PSI with actual flow
✅ Paired with Prime Force scissor hoists, which have thicker cylinder walls, our systems can handle higher pressures
✅ This results in better lifting performance, especially at the most critical part of the lift – the beginning

Comparing a Generic Pump vs. Primary Mover 2.2 kW

How to Improve the Performance of Your Scissor Dump

If your hoist is struggling to lift, the solution is often simple:
✅ Upgrade to a hydraulic power unit that delivers full PSI with flow
✅ Ensure your battery is fully charged (low voltage = weak performance)
✅ Consider our Road Charger system to keep your system powered

Final Thoughts – The Right Power Unit Makes All the Difference

A scissor hoist is only as good as the hydraulic power behind it. If your system is topping out at 2800 PSI, you’re missing out on up to 16,632 lbs of extra lifting force.

Why Choose Primary Mover & Prime Force Scissor Hoists?

• Stronger Cylinders: Prime Force 500 series uses 5.5” cylinders, and the 600 series uses 6.5” cylinders, giving you more lifting power than generic competitors.
• Higher Pressure Capability: Thicker cylinder walls handle higher pressures safely.
• Built for Higher Pressures: Prime Force scissor hoists feature **thicker cylinder walls**, allowing them to handle increased PSI safely and maintain durability under extreme loads. This ensures your hydraulic system operates efficiently even at **3200+ PSI**, where weaker cylinders may struggle or fail.
• Powerful Hydraulic Units: Primary Mover 2.2 kW reaches 3500 PSI, ensuring stronger, more reliable dumping.

Upgrading to a Primary Mover 2.2 kW power unit with a Prime Force scissor hoist unlocks the full potential of your dump system, ensuring faster, smoother, and more reliable dumping—even under heavy loads.

Need help choosing the right pump for your setup? Contact us today and let’s get your dump system running at its best.