Katool KT-RJ50: the collapsed height is the number that decides this purchase

Most rolling jacks are sold on capacity. Capacity is rarely the problem. What actually stops a rolling jack from being useful is geometry: whether it will go under the vehicle at all once the lift is raised, and whether the platform reaches the vehicle's designated lift points when it gets there.

The KT-RJ50 publishes both figures, which is more than most listings in this class do. It starts at 5.3" collapsed and lifts to 18.3", on a platform adjustable from 36.6" to 52.6" in length. If you have ever tried to slide a jack under a low car that is already sitting on the runways, you know which of those numbers you would check first.

Will It Fit?

• Under the vehicle. 5.3" collapsed. That is the clearance the jack needs beneath the lowest point it must pass under while rolling into position. Measure the lowest car you regularly service, not the average one.
• Up to the lift points. 18.3" of lift at the top of the pad, which is the working range you get once the platform is under the vehicle.
• Across the frame. A platform adjustable from 36.6" to 52.6" long, so the pads can be set to a vehicle's actual lift points rather than to wherever the jack happens to sit.
• Your lift. Designed for the Katool KT-4H110 and the KT-4H850 four-post lifts. If you own something else, ask us before ordering rather than assuming a rolling jack is a rolling jack.
• Air supply. The KT-RJ50 is air over hydraulic and requires an external compressed air supply. It is not self-contained, and a shop without a compressor at the lift bay needs to solve that first.
• Your responsibility. Confirming your lift model, your air supply and the clearance under the vehicles you service is the buyer's job. We can give you the jack's numbers; we cannot see your bay.

Air over hydraulic, and why the operator notices

The KT-RJ50 uses shop air to drive a hydraulic circuit rather than asking a technician to pump a handle. The practical difference is not speed, it is consistency: a hydraulic circuit fed by regulated air lifts at the same rate every time, so a vehicle comes up evenly instead of in the surges that a hand pump produces. On brake and wheel work, where the vehicle needs to arrive at a steady height and stay there while it is worked on, that even rise is the point.

It also removes the physical effort. A technician who has to pump a jack thirty times a day is a technician who eventually finds a shortcut, and the shortcuts around lifting equipment are the ones that hurt people.

The scissor mechanism and level lifting

The KT-RJ50 uses a scissor-style mechanism, which is what allows the platform to stay level throughout its travel rather than arcing as it rises. Level travel keeps the vehicle's weight distributed across the pads as intended and keeps the contact patches where they were set at the start of the lift. On a jack that arcs, the pads creep as the vehicle rises, and creep at a lift point is exactly what nobody wants.

Three locking height positions hold the platform where it is put, so the jack is not relying on hydraulic pressure alone to keep a vehicle up while someone works underneath it. That is the design decision worth paying attention to on any lifting product: what holds the load when the hydraulics are not.

Built to stay in service

The frame is powder-coated steel. That is a corrosion decision rather than a cosmetic one, because a rolling jack spends its life on a shop floor where brake fluid, road salt off vehicle undersides and washdown water all land on it. At 441 lbs the unit has the mass to sit stable on the runways, and the low-profile build is what keeps that mass out of the way when the jack is not in use.

The whole design is deliberately simple. There is nothing on it that needs calibrating, nothing that needs a software update and nothing that fails in an interesting way. For equipment that is used several times a day by different people, simple is the correct specification.

Perfect For

• Shops running a KT-4H110 or KT-4H850 that need wheels-free service from a drive-on lift.
• Brake, tire and suspension work where the vehicle should stay on the lift instead of moving to another bay.
• Low-clearance vehicles, where a 5.3" collapsed height is the difference between a usable jack and one that will not go under.
• Busy general bays that want a second capability from a lift they already own rather than a second lift they have nowhere to put.

What is in the box

• KT-RJ50 rolling jack with a scissor-style lifting mechanism
• Powder-coated steel frame with an adjustable-length platform
• Air over hydraulic operation with three locking height positions

An external compressed air supply is required and is not supplied. The lift itself is a separate product, and adding this jack does not change the lift's own rated capacity.

Specifications

Certification, stated plainly

Nothing in this product's data claims a third-party North American safety listing, and this page will not imply one. On equipment that holds a vehicle in the air the distinction is worth taking seriously rather than glossing: some commercial insurance policies, some fleet and municipal operations and some local jurisdictions require a named listing on lifting equipment specifically. If any of those apply to you, confirm the requirement with the body that imposes it before you order, and ask us for whatever documentation the manufacturer provides. Independently of any paperwork, this jack is only as safe as the vehicle lift points it is set to and the four-post lift it is used on.

Warranty

The KT-RJ50 is listed with a 1-year parts-only warranty. Katool's own warranty document is the governing text and this listing does not reproduce it, so ask us for the current version if the detail matters to your decision. Whatever the terms say, do not take a faulty unit apart before the claim has been registered - a dismantled jack is almost always an unpayable claim, however clear the fault seemed at the time.

Shipping and delivery

At 441 lbs this is a freight shipment, delivered to addresses in the lower 48 states. The freight figure is generated live at checkout from the address you enter, so it reflects the carrier's current rate rather than a number that has gone stale on a page. The receiver is responsible for getting the crate off the truck, so arrange a forklift or a suitable machine, or select a terminal pickup, which many buyers find easier because the terminal already has the equipment. Residential delivery carries a residential fee, applied at checkout when you select it.

Inspect the crate before you sign for it. Crushed corners, torn shrink, broken banding and any evidence of a drop should go on the bill of lading in writing while the driver is still there, backed by photographs. A clean signature is the carrier's proof that the jack arrived undamaged.