12K Hydraulic Trailer Jack Add-On Kit for Existing Double-Acting Systems – Bolt-On or Weld-On
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We offer the following methods of delivery:
- Same day Freight Shipping when ordered Mon-Fri before 12pm central time. (excluding holidays)
- Pickup from our Mandeville, Louisiana warehouse
- In some cases, free shipping - please contact us: sales@primarymover.com or call 985-888-6554
Add a 12K hydraulic jack to your existing double-acting system
The Primary Mover 12K Single Hydraulic Trailer Jack Add-On Kit adds powered jack extension and retraction to a compatible existing double-acting hydraulic system. Choose bolt-on or weld-on mounting and use your existing power unit to operate the dump circuit or jack through the included manual selector valve.
The kit combines our 12,000 lb hydraulic trailer jack with a 20-inch stroke, dual counterbalance valves and the hydraulic hoses, fittings and selector valve listed below. Premium jack construction includes a stainless steel cap, hot-dip galvanized foot, galvanized inner sleeve and rigid hydraulic piping on the cylinder.
Hydraulic power unit and remote control are not included. This is an add-on package for an existing compatible system. For a single-acting, power-up/gravity-down setup, use our jack-only listing with the appropriate X-Block kit.
- 12,000 lb rated jack lifting capacity.
- 20-inch hydraulic stroke.
- Double-acting operation: powered extension and retraction.
- Dual counterbalance valves: load-control functions for both cylinder sides.
- Included hydraulic hookup components: jack hoses, connection hoses, adapters and manual selector valve.
- Mounting choices: bolt-on or weld-on.
- Existing power unit: retain a compatible double-acting hydraulic system.
- 12-month limited jack warranty, subject to warranty terms.
One power unit, two selectable functions
The included manual selector ball valve switches between the existing dump circuit and the added hydraulic jack circuit. Select the function you need, then operate it using the compatible existing power unit and controls.
The jack requires pressure supplied to one cylinder side for extension and to the opposite side for retraction. Your existing hydraulic system must provide suitable double-acting operation, pressure and flow for the installation.
Operate one selected circuit at a time. Stop the pump before changing the selector valve position. Identify extension and retraction during installation before operating the jack under load.
Dual counterbalance valves for both jack positions
A jack should stay extended while supporting the trailer and stay retracted when stowed for travel. The Primary Mover jack uses dual counterbalance valves to provide load-control functions for both sides of its hydraulic cylinder.
This arrangement helps resist unintended retraction under load and unintended extension when the leg is retracted. During lowering, the valves control outgoing oil flow to help prevent the load from driving the cylinder ahead of the commanded hydraulic movement.
Counterbalance valves support load holding and controlled movement. A basic check valve or pilot-operated check arrangement does not automatically provide the same motion-control function. Actual operating smoothness depends on the complete system, valve settings and load.
Learn why dual counterbalance valves matter on hydraulic trailer jacks .
Premium jack construction
- Stainless steel cap: a corrosion-resistant component at the top of the jack.
- Hot-dip galvanized foot: corrosion protection for the ground-contact component.
- Galvanized inner sleeve: protection for the exposed moving section.
- Rigid cylinder piping: hard piping on the cylinder rather than a flexible hose running along its side. External hookup hoses are included with this kit.
- Painted steel outer tube: a 4-inch-square jack structure.
What the Add-On Kit includes
- One 12K hydraulic trailer jack assembly with double-acting cylinder, 20-inch stroke, dual counterbalance valves and the selected bolt-on or weld-on configuration
- Two 72-inch hydraulic hoses with JIC-6 straight and 90-degree end fittings
- Two 18-inch hydraulic hoses with JIC-6 straight and 90-degree end fittings
- Eight straight adapter fittings — SAE-6 male to JIC-6 male
- One manual selector ball valve with aluminum knob
Need additional hose reach? A 120-inch jack-hose upgrade is available at additional cost. Confirm the required length before ordering.
Not included: hydraulic power unit, remote control, battery, X-Block adapter or optional transition plates.
Choose the right package for your existing power unit
Existing double-acting power unit
This Add-On Kit is intended for a compatible existing double-acting hydraulic system. Confirm its pressure settings, flow, connections and control arrangement before installation.
Existing single-acting power-up/gravity-down power unit
A conventional single-acting circuit does not provide powered movement in both directions for this double-acting jack by itself. For that setup, purchase the jack-only option and add the X-Block Poly Tank or Steel Tank Kit.
The X-Block package supplies the directional adapter, selector valve, hoses and fittings for its intended single-acting installation. Choose its tank-return fitting to match your existing reservoir connection.
No existing power unit
Choose a complete powered jack kit from our hydraulic trailer jack collection or use the Jack Kit Selector to narrow down your options.
Bolt-on or weld-on mounting
Select the mounting configuration that suits your trailer. For the bolt-on version, compare the hole pattern and mounting dimensions with your existing structure. For the weld-on version, provide suitable structural support and welding for the intended load.
A compatible bolt-on transition plate may provide another mounting option. Transition adapters are sold separately; confirm compatibility before ordering.
Match lifting reach and clearance to your trailer
The jack provides 20 inches of hydraulic travel. Useful lifting reach also depends on mounting height, retracted dimensions, trailer coupling height and required ground clearance.
A longer stroke is not automatically a better fit. Compare the complete mounting layout, including how far the jack projects above and below the trailer frame. Use the product drawings and manual to confirm fit.
Add-On Kit questions and answers
Does this kit include a hydraulic power unit?
No. This package adds one jack and the listed hydraulic hookup components to an existing compatible double-acting system. It does not include a power unit or remote control.
Can one power unit operate my dump body and this jack?
Yes, when the existing power unit and hydraulic circuit are compatible. The manual selector valve chooses the dump circuit or jack circuit. Operate one function at a time and stop the pump before switching.
Will this kit work directly with a single-acting power-up/gravity-down pump?
This package alone does not add the directional control needed to power a double-acting jack in both directions from a conventional single-acting circuit. Choose the jack-only listing with the appropriate X-Block kit for that installation.
What does this kit add compared with buying the jack by itself?
It adds two 72-inch jack hoses, two 18-inch connection hoses, eight straight SAE-6-to-JIC-6 adapter fittings and a manual selector ball valve.
Why does the jack have dual counterbalance valves?
They provide load-control functions for both cylinder sides, helping maintain the extended or retracted position and control load-driven movement during operation.
Can I order longer jack hoses?
Yes. A 120-inch jack-hose upgrade is available at additional cost. Confirm the routing and required length before ordering.
Does the 12K jack rating increase my trailer’s capacity?
No. The jack’s rated lifting capacity does not increase trailer GVWR, frame capacity or other component ratings. Remain within the applicable limits for the complete installation.
Manual, warranty and demonstration
- Download the Primary Mover 12K Hydraulic Trailer Jack Manual
- View warranty coverage and terms
- Learn about dual counterbalance valves
Need help confirming compatibility? Call 985-888-6554 or email sales@primarymover.com with photos of your existing power unit and trailer mounting arrangement.
