CEMB SM645HPA: a press arm that works both sides of the wheel

The letters on the end of this model number are the whole story. HPA is the two-sided press arm package: a press arm, a press follower, and two tire lifter discs. The same base machine is also sold with a single-sided arm, and the difference between them is not a matter of trim level — it is the difference between pressing one bead at a time and being able to control both sides of a stiff, uncooperative tire while the table turns.

That capability exists for one reason: high-performance and run-flat tires with sidewalls that will not fold, mounted on wheels with drop centres deep enough to lose a bead in. Those fitments are now ordinary rather than exotic, and they are what breaks an otherwise perfectly good tire changer.

What the two-sided press arm actually does

A tire mounts or demounts only when the bead opposite the mount head is sitting in the deepest part of the rim well. A stiff sidewall does not want to be there and climbs straight back out the moment nothing is holding it. When that happens the mount head is levering against a bead with nowhere to go, and the outcomes are a scored rim, a damaged bead, or a technician with a bar and an opinion.

The press arm holds the bead down mechanically for the full rotation. The press follower tracks with it. Working the wheel from both sides means the operator is not fighting a bead that keeps escaping on the side they are not on, and the two tire lifter discs take the physical work of raising and supporting the tire during the operation, which on a heavy performance fitment is real weight repeated many times a day.

The automatic tilt-back column

The mount-demount arm is on an automatic locking tilt column, and it re-positions itself for the next wheel without adjustment. This is the feature nobody photographs and everybody notices. On a manually adjusted machine, every wheel of a different size means re-setting the arm, and every re-set is a small opportunity to set it wrong — too close and the head marks the rim, too far and the tire will not come over. Automatic locking removes that per-wheel decision, so wheel four of a set is set up exactly like wheel one, by the machine, at the same speed.

Clamping and the bead loosening system

Table clamping uses dual cylinders with a Space-Saver under-table adjustable clamping range, so the clamping mechanism sits below the table rather than eating into the working area on top of it. The practical result is more room around the wheel for the press arm and for the technician's hands, which on a machine whose entire purpose is difficult fitments is not a small thing.

The bead loosening system is adjustable to the correct angle for the diameter and width of the tire in front of it. Setting the angle correctly is what separates loosening a bead from denting a rim flange: a shovel arriving at the wrong angle concentrates force in the wrong place. Being able to set it per tire, rather than accepting one fixed geometry, is what makes the machine usable across a wide fitment mix.

Inflation, in two stages

Bead sealing inflation is via two-stage jets, and the tire inflator includes a safety limiter. Seating a bead is the single most dangerous routine operation on a tire changer, because it is the one where energy is being stored in a component that can fail. A limiter that caps inflation pressure is a mechanical answer to that risk rather than a procedural one, and mechanical answers are the ones that still work when the shop is busy and somebody is distracted.

Will it fit your shop?

Power is 110 VAC, single phase, 50/60 Hz — a conventional supply, which is genuinely convenient for a machine of this capability, and it means many shops can site it without new heavy-current work. The machine also needs a compressed-air supply for clamping, the press system and inflation, so the bay needs a proper air drop rather than a shared coil. Providing the electrical circuit and the air supply, and having the electrical work done by a licensed electrician to local code, is the customer's responsibility.

Shipping weight is 1,050 lbs (476 kg), so measure the route in before delivery day: the door, the threshold, and any turn tight enough to matter. Leave clear working space around the machine as well — the tilt column needs room behind it, and the press arm needs room beside it.

Perfect for

• Performance and specialist tire shops — the machine is specified around exactly the fitments that defeat a general-purpose changer.
• Dealership service departments — where the fitment mix is whatever the manufacturer sold and refusing a wheel is not an option.
• High-volume independents — the automatic tilt-back column pays for itself in setups not repeated.
• Shops with a wheel-damage problem — most rim damage happens when a bead is being forced rather than held; this machine is built to hold it.

What's in the box

The HPA package includes the press arm, the press follower and two tire lifter discs. The machine is supplied fully assembled and tested. A polymer mount head kit is listed as an option rather than standard equipment on this model, so if you work on alloy faces, specify it deliberately — ask us and we will confirm what is going in the crate before the order goes through.

Specifications

Capacity

Drive, air and shipping

One measurement worth a phone call

Published figures for the maximum wheel width differ: the specification gives it as 13" (380 mm), and those two values do not describe the same width — converted, 380 mm is nearer fifteen inches than thirteen. Both are reproduced above exactly as CEMB publishes them, because a width limit is worth getting right before the machine arrives. If you regularly mount wheels wider than 13", contact us before you order and we will confirm the current maximum with CEMB in writing.

Certification, stated plainly

We do not publish a third-party North American safety listing for this changer, and we will not imply one. The manufacturer's data covers performance and dimensions; it does not include an independent listing, and a manufacturer's own declaration is not the same thing.

Insurers, corporate fleet policies and some local inspection authorities can require a named third-party listing before signing off an installation. If you buy under any of those, ask us to confirm what documentation ships with the machine before you order rather than after.

Shipping and delivery

This ships freight, to the contiguous United States only. Rather than print a shipping price that would be out of date within the quarter, we quote it live at checkout against the ZIP code you enter. Residential delivery carries a residential fee, added at checkout.

The unload is the part people underestimate: a crated machine needs a forklift or a dock at your end, and the carrier brings the freight, not the equipment to lift it off. If you have neither, say so and we will arrange terminal pickup. Inspect before you sign, and record anything you see on the bill of lading with the driver present.

Warranty

A manufacturer's warranty document exists for this machine and it is the text that governs. You will not find a coverage period quoted here, and that is deliberate — we would rather hand you the document than a paraphrase. Ask and we will send it over.

House rule on claims: do not disassemble before you call. Pulling a cover to investigate can end a warranty claim before it starts. Photograph it, note the serial number, and speak to us first.