AMGO RJ-20A: a 20,000 lb rolling jack that meets an uneven frame flat, on shop air

What separates a rolling jack you trust from one you fight is where it touches the vehicle. The RJ-20A's saddle is a double-screw design, so the pad can be set flat against a chassis rail that is not flat — which, on a full-size truck, is most of them — and the 3″ and 6″ extension adapters are in the crate as standard rather than sold on afterwards, so it reaches up into a high frame the day it arrives.

It is driven by shop air, not electricity: there is no circuit to run, only a line to reach. And it is a heavy-duty jack in the literal sense — 20,000 lbs of capacity, a reinforced scissor structure and an oversized hydraulic cylinder.

Will It Fit?

A rolling jack is bought for a lift you already own, so the fitment questions are about your lift rather than your building. Measure before ordering - the measuring is the buyer's responsibility.

• Runway spacing — the figures here are contested. This page lists a support base adjusting from 47 7/16″ to 63 3/16″, and the manufacturer publishes a narrower band at both ends. Measure between the inside faces of your runways where the jack will actually sit, not at the ramp end, and then check that measurement with us.
• Jack width. 25 1/2″ overall - the space it occupies between the runways when it is parked out of the way.
• Clearance underneath. The jack stands 14 9/16″ at its lowest. That is the height it needs to roll into position beneath the vehicle, so it is the figure to check against the lowest thing your four-post will be carrying.
• Reach — also contested. This page lists an arm-pad span of 45 1/4″ to 72 5/8″; the manufacturer publishes a shorter maximum reach. Reach is what lets the pads meet lift points on a small car and on a full-size truck without repositioning, so settle it before you order rather than after.
• Air. The pump is pneumatic-hydraulic and runs at 0.8Mpa. There is no electrical connection to make, but a compressed air line has to reach the lift, and that is worth arranging before the jack arrives rather than after.

Fit is decided by your runways, not by the capacity badge

Rolling jacks are frequently sold as though any jack fits any four-post. They do not. A fixed-width jack is built for one runway spacing, and if your lift is wider or narrower than the one it was designed around, it either will not seat or seats badly with the load in the wrong place. The extendable lower sliding assembly on the RJ-20A is strengthened and thickened so that it holds the jack steadily between the runways across its adjustment range, not merely so that it reaches.

That is also why it is worth buying a jack rated well above the axle load you expect. A 20,000 lb rating is not about lifting twenty thousand pounds. It is about what the frame is doing when you lift eight thousand, off-centre, on one corner, for the four hundredth time.

The saddle, and why the pad is a two-screw design

The frame saddle pad assembly uses a double-screwing design. Two independently adjusted screws let the pad sit flat against a chassis that is not flat, which on a full-size truck or a heavy-duty vehicle is most of them. A single-screw or fixed saddle contacts a sloped frame rail on an edge instead of a face, and edge contact under twenty thousand pounds of rating is exactly how frames get dented and pads get squeezed out sideways. The 3″ and 6″ extension adapters stack onto that saddle to reach up into a high chassis - included as standard, which is not universal in this category and is worth checking when you compare.

Rollers, arms and the handle nobody mentions

The rollers use a patented floating design in hardened stainless steel, zinc plated. A rolling jack spends its life dragged along gritty steel runways, and the rollers are what wear out first on a cheap one.

The guardrail doubles as a booster handle: something to push against when shifting a heavy jack along a runway, and a shield that keeps the oil hose from being trodden on. The kind of detail you notice only when it is absent.

Perfect For

• Heavy-duty and full-size truck work on a four-post - the case the capacity and the saddle design were built around.
• Commercial service bays that need wheels-free work on a lift bought for drive-on convenience.
• Fleet operations, where brake and suspension work on the same vehicles happens week after week.
• Shops with mixed runway spacings across more than one four-post, thanks to the adjustable base.

What is in the crate

• The rolling jack with reinforced scissor structure and oversized hydraulic cylinder
• Pneumatic hydraulic pump
• Double-screwing frame saddle pad assembly, fitted as standard
• 3″ and 6″ extension adapters, included as standard accessories
• Extendable lower sliding assembly and the ergonomic guardrail booster handle

Not supplied: the compressed air line and its fittings are yours to provide.

Specifications

Measure your runways, then check the spans with us

Measure your own four-post and confirm the support-base and arm-reach spans with us in writing before you order. The fit figures printed on this page are ones the manufacturer's current published specification disagrees with. Set against ours it gives a narrower support-base range at both ends, a shorter maximum arm-pad reach, a lower maximum lifting height both with and without the adapters, and a much shorter lifting time. On a rolling jack the first two are the whole purchase: they are what has to straddle the runways of a lift you already own, and a jack that cannot span them is scrap in a crate.

We assert neither set of figures. Ours have been republished by other sellers of this jack word for word, so numbers agreeing across the internet says nothing about which sheet is current — and printing a second set here would only leave you choosing between two. Send us the make of your four-post and the measurement between the inside faces of its runways. We will get the answer from the manufacturer and put it in writing before you commit.

Certification, stated plainly

The product data we hold for the RJ-20A states no third-party safety certification or listing of any kind, and we will not imply one by decorating the page with badges. That is not the same as saying none exists - it means we have not seen it. If your insurer, your fleet policy or your local code requires a specific listing on lifting equipment, tell us before you order and we will put the question to the manufacturer in writing. For many shops it never comes up; when it does, a vague answer is worse than none.

Shipping and delivery

The RJ-20A ships by freight truck within the lower 48, quoted live against your address at checkout rather than estimated. A rolling jack is compact and extremely dense - much heavier than it looks, which catches people out. Unloading is the receiver's responsibility, so plan for a forklift rated for the crate or book a collection from the carrier's terminal, which already has the equipment and a dock. Residential delivery carries a residential fee, applied at checkout.

Inspect the crate before signing. Check the saddle and arms for bending, the scissor structure and hose for damage or weeping oil, and confirm both extension adapters are in the box; write anything you find on the bill of lading with the driver still there, and photograph it. Sign clean and the carrier holds proof the shipment arrived intact.

Warranty

The product data for the RJ-20A does not publish a warranty term, so we will not print one. Ask us before you buy and we will send you the manufacturer's current written terms as they apply to your order. Our own claims process is set out at mechanicsuperstore.com/pages/warranty-claims.

One warning applies to every hydraulic jack: if something fails, do not take apart the pump, the cylinder or the saddle assembly before a claim is opened. A disassembled component is normally treated as a modified one, and that is the fastest way to lose cover you were entitled to. Photograph the fault, note the serial number, and call us first.