Choose Primary Mover 12V for our standard power-up and power-down setup, KTI 12V when you want the additional gravity-down function, or Primary Mover 24V to match an existing 24V battery system. For larger double-acting hoists that need more oil flow, we also offer a separate twin-motor 24V power unit.
We are a KTI dealer, and we respect the engineering and performance that have made KTI an established name in mobile hydraulics. We enjoy selling and supporting their products. Their performance has also been an important benchmark as we developed our own Primary Mover power units.
Our approach combines a larger motor with a more robust starting contactor and a focus on delivering useful flow at the pressures our hoists need. The right choice depends on your preferred controls, electrical system and application.
Compare the standard scissor-hoist power-unit choices
| Feature | Primary Mover 12V | KTI 12V kit option | Primary Mover 24V |
|---|---|---|---|
| Operation | Power up / power down | Power up / power down / gravity down | Power up / power down |
| Remote | Two-button | Three-button | Matching two-button 24V control |
| Main reason to choose it | Our standard 12V setup with a 2.2 kW / approximately 3 HP motor | KTI engineering, brand preference and the gravity-down option | Compatibility with a 24V battery system |
| Battery system | 12V | 12V | 24V |
| Power-unit warranty | One year | One year | One year |
This guide applies across our Prime Force scissor-hoist lineup. Available selections vary by hoist and package. Confirm the power unit, reservoir capacity, voltage and controls listed for your particular kit. KTI and Primary Mover also make other power units with different circuits.
Browse Prime Force scissor hoists and available kit options.
Why choose a Primary Mover power unit?
A 2.2 kW motor for demanding lifting applications
Our standard Primary Mover 12V double-acting unit uses a 2.2 kW motor, approximately 3 horsepower. We selected this motor to provide the drive power needed when a properly matched pump is working against a heavy load.
Motor size is only one part of performance. The pump, valves, wiring and battery must work together. Our development focus is useful oil flow under load, particularly as pressure rises during the difficult beginning of a dump cycle.
A more robust starting contactor
The motor-start solenoid, also called a contactor, is a common service issue in our experience with hydraulic power units. For our current 12V design, we moved from a 200-amp-rated contactor to a 300-amp continuous-current-rated contactor to better support the larger motor and demanding electrical load.
This is the high-current switch that supplies the motor, separate from the hydraulic valve solenoids. Its rating does not mean the motor always draws 300 amps, and it does not make the complete power unit continuous-duty. Follow the unit's operating and cooling requirements.
Pressure lifts the load; flow determines how quickly it moves
A maximum-pressure number alone does not tell you how well a power unit will dump a loaded bed. Pressure produces cylinder force. Oil flow determines cylinder speed. You need useful flow at the pressure required to move the load.
Our published scissor-hoist capacity charts use 3,200 PSI. A unit limited to a lower lifting pressure can leave the same hoist with substantially less available cylinder force. For example, at otherwise equal conditions, 2,500 PSI produces about 78% of the theoretical cylinder force available at 3,200 PSI.
A unit can also reach its relief setting while delivering little or no useful flow to a stalled cylinder. When comparing performance, look at flow under load, battery voltage at the motor and the complete installation—not just a no-load flow figure or a pressure label.
Use the approved pressure setting for the hoist and all connected components. A lower-rated unit should not be turned up beyond its specifications to imitate a different model.
Read Why Your Scissor Dump Isn't Dumping — and How to Fix It.
Why choose KTI?
KTI builds excellent hydraulic power units, and its engineering deserves credit. Customers may already know the brand, have had good experience with its equipment, or prefer its controls. We are happy to help customers choose KTI when it fits their needs.
For the KTI configuration discussed here, the most noticeable functional difference is the three-button remote: power up, power down and gravity down. The gravity-down option lets the weight of the raised body lower the hoist without running the main pump motor, when the load and installation allow it.
Gravity down requires the right hydraulic circuit
A double-acting cylinder needs oil management on both sides of the piston. As the cylinder retracts, oil leaves the base end while the rod-side chamber needs make-up oil. The circuit must accommodate that movement as well as the unequal volumes on the two sides.
In our development testing, simply adding a gravity-return path to a conventional double-acting arrangement did not provide the same behavior we value in the KTI system. Depending on the circuit, issues can include increased reservoir demand, insufficient rod-side make-up oil and a delay while powered operation refills that chamber.
A larger tank alone does not solve the make-up-oil requirement. This is why we offer the purpose-designed KTI three-button configuration when customers want that feature. The number of buttons by itself does not establish how a competing unit handles oil during gravity lowering.
View KTI's power-up, power-down and gravity-down installation instructions.
How much battery does gravity down save?
Gravity down avoids running the main motor during lowering, so it saves battery energy and eliminates that motor's noise during the descent. The amount saved depends on the current and time that powered lowering would otherwise require.
Powered lowering can draw considerably less current than a heavy lift because the raised body's weight helps retract the cylinder. As an illustrative example, not a measured result for every installation, assume a 12V unit averages 70 amps during a 25–40-second descent:
| Lowering time | Battery charge used | Approximate energy used |
|---|---|---|
| 25 seconds | 0.49 amp-hours | 5.8 watt-hours |
| 40 seconds | 0.78 amp-hours | 9.3 watt-hours |
The calculation is amps × seconds ÷ 3,600. Gravity down avoids most of that motor consumption, although the controls and valve coils still use some electricity. Repeated cycles can make the savings useful; a percentage increase in dumps per charge requires measurements of the complete lift-and-lower cycle.
Choose gravity down because you value the feature. It does not replace the need for a healthy battery, proper cables and adequate charging.
Battery placement and cable length matter with either brand
A strong power unit needs a battery capable of supplying its current demand. Weak batteries, undersized cables and poor connections can reduce performance regardless of the name on the motor.
Where practical, position the auxiliary battery close to the power unit. Measure the actual routed cable length, including drops beneath the chassis, bends, rises and service loops. An eight-foot straight-line distance can become a much longer cable run after installation.
Voltage drop depends on the complete electrical circuit, including the positive supply and negative return. When using a manufacturer's cable chart, check whether its length means a one-way cable run or the total circuit length. Use the requirements for your exact power unit and installation.
Find power-unit installation manuals and battery-cable guidance. Have your battery specification and actual cable routing ready if you need help selecting an installation.
When should you choose Primary Mover 24V?
Choose our standard 24V double-acting option when your truck or trailer already uses a 24V battery system. Military vehicles and other equipment may use 24V, and matching that voltage avoids adding a separate 12V supply for the hoist.
24V does not automatically mean a faster dump cycle. At comparable electrical power, doubling voltage approximately halves current. Actual lifting speed still depends on pump flow at the required pressure.
The standard 24V option uses voltage-matched electrical components and costs more than our standard 12V configuration. Select it for the electrical system you are building.
Need more flow for a larger hoist? Meet the twin-motor 24V unit
Our separate Primary Mover Twin Engine double-acting 24V power unit uses two 2.2 kW motors—approximately 6 HP combined—and a 15-quart reservoir. It is a different product from the standard single-motor 24V kit option.
Larger bores and longer strokes require more oil to complete a cylinder movement. With the same pump flow, that means longer travel times. The twin-motor unit is designed to provide more flow for demanding double-acting applications, including suitable 600-series scissor-hoist installations.
The additional pumping capacity is what improves speed. A particular installation's improvement depends on pressure, flow restrictions and electrical supply; it is not a promise that every dump cycle takes half the time.
Two suitable, matched 12V batteries wired in series can provide its 24V supply. Series wiring doubles voltage while retaining the amp-hour capacity of one battery; the batteries, cables and charging equipment must suit the complete system.
This unit is sold separately; do not assume it is included in a hoist kit or offered in every kit's selection menu. Contact us to confirm compatibility and package availability for your hoist.
Explore the Primary Mover twin-motor 24V double-acting power unit.
Service, replacement parts and warranty
We sell both brands and can help with selection and troubleshooting. When requesting support, send the unit's model or part number, photos and a description of the problem. For slow or weak operation, battery voltage under load and the actual cable sizes and lengths are useful starting information.
Motors, starting contactors, valve components, pumps, reservoirs and remotes must be matched to the specific unit. Contact us to identify the correct service part and confirm availability before ordering; similar appearance does not establish interchangeability.
The Primary Mover and KTI power units offered in these kits each carry a one-year warranty. The hoist's separate 36-month warranty does not extend the power-unit coverage.
Read Primary Mover Product Warranties and support details.
Our recommendation
- Primary Mover 12V: Our standard choice for a compatible 12V scissor-hoist build using power-up and power-down controls.
- KTI 12V: Choose it for KTI brand preference and the additional gravity-down function.
- Primary Mover 24V: Choose the standard unit to match a 24V electrical system.
- Twin-motor 24V: Discuss it with us for a larger double-acting hoist where additional flow is a priority.
Start with the lifting capacity and installation geometry your build requires, then match the power unit's pressure, working flow, reservoir capacity, controls and voltage. A larger power unit cannot increase a hoist's structural rating or correct unsuitable mounting geometry.
Browse all Prime Force scissor-hoist kits
Use the Scissor Hoist Selector
See how mounting space and capacity compare: PF-310 vs. PF-416
See a kit-selection example in the PF-310 purchasing guide
Need help matching a power unit to your build? Call 985-888-6554 or email sales@primarymover.com.