The Rotary N2121 arm restraint gear is the direct replacement for the Rotary lift it came off of. Cross-referenced as ALS-7545-17, it is the genuine Rotary part — same part number, same fit, and same working specification as the one already on your lift. Ordering the Rotary arm restraint gear from us gets you the OEM piece that matches the lift, not an aftermarket knock-off that is close but not the same.

Specifications

• Part number: ALS-7545-17
• Brand: Rotary
• Type: Genuine OEM arm restraint gear
• Fits: A10i, A10i EH-1, A10i EH-2, S10i, S10i EH-1, S10i EH-2, S10i EH-4, SPO10, SPO12 EH-1, SPO12 EH-2, SPO15 300 Series, SPO18 300 Series
• Lift type: 2-post lift

Lock parts wear slowly but steadily every time the lift cycles. Each engagement bangs the pawl against a tooth; over thousands of cycles the contact faces peen over and round off. Dirt and dried grease build up in the pivot until the pawl gets lazy. A commercial lift that racks up cycles all day will round its lock teeth years before a low-use lift does — but neglect and rust can age either one fast.

The locks are the lift's mechanical backup — the part that actually holds the vehicle up once it's raised. A spring-loaded pawl drops into a toothed ladder at each column, and the lift rests on steel, not on hydraulic pressure. Hydraulics raise the lift; the locks are what let you work under it. Every click you hear on the way up is a pawl catching a tooth, ready to catch the whole load if pressure is ever lost.

What lifts this arm restraint gear fits

This arm restraint gear fits the lift models below. Click a model to open its visual parts breakdown — the exploded drawing with every part numbered, so you can confirm this is the right part for your exact lift before you order.

• A10I — see the exploded parts breakdown for this lift
• S10I — see the exploded parts breakdown for this lift
• SPO10 — see the exploded parts breakdown for this lift
• SPO12 — see the exploded parts breakdown for this lift

Related parts for this lift

The parts below are commonly ordered alongside this one — cables, sheaves, seals, and hardware wear on similar schedules, and most repairs go faster when the whole set is done in one visit.

• Outer Rear Swing Arm - Rotary N2150-1
• Inner Rear Swing Arm Kit - Rotary N2103-1
• Arm Swivel Pin - Rotary N2154
• Arm Restraint Gear (Adjustable) - Rotary SVI Exclusive
• Arm Restraint Gear (Not Adjustable) - Rotary N2122
• Outer Rear Swing Arm - Rotary N2151-1

Replacing your arm restraint gear

Lock work usually pairs with checking the release and the leveling, since uneven clicks can come from the ladder, the pawl, the release, or stretched cables. Replace the worn parts, then adjust so every lock lands together and releases together. Chasing that timing down correctly is the whole job, and the full walkthrough covers how. Full step-by-step: how to replace lift arm restraint gears.

Find the right part for your lift

Want to be sure before you buy? Pull the model and serial off your lift's plate and open our Rotary parts lookup to open the exploded parts breakdown for your model — find your part on the drawing and you know it fits. New to finding your model number? our guide to finding your model number covers it, or send a photo of the plate and we will read it for you.

Signs the locking system needs attention

Test engagement under the lift's own weight: raise it, then lower onto the locks and watch each pawl seat fully into a tooth. Any pawl resting on the tip or shoulder of a tooth instead of down in the root isn't fully engaged, even though it looks set. Shallow engagement usually traces to a worn tooth, a worn pawl nose, or the lift sitting unlevel.

Parts commonly replaced at the same time

Since the lift has to come down to its locks safely on both sides, service the lock hardware as a unit — latch, pawl, spring, cable, both columns. Half a repair leaves uneven engagement. We will build the full lock kit for your lift so it catches and releases together the way it should.

Safety notes

Every lift is designed to rest on its locks, not its hydraulics — which is why worn lock hardware is so dangerous. Replace latches, pawls, and release cables before they hesitate, verify both columns lock and release in step, and take any lift with an unreliable lock out of service on the spot.

Before you order

Before ordering lock parts, confirm your lift's model and serial — latch, pawl, and release-cable designs changed over the years. Replacing the lock hardware as a set on both columns keeps engagement even, so order for both sides unless you know only one is worn. Call if you need to match an older design.

Not sure this fits? Here's how to check

Pull the number off your lift's model plate first — model and serial both. Manufacturers run mid-cycle revisions that keep the model name but change hardware, so two lifts with the same name on the column can take different parts. The serial is what removes the guesswork.

Second check: compare the old part against this listing before you order. Length, mounting pattern, and thread sizes tell most of the story. If anything doesn't line up, or if the old part is too worn or broken to measure, call us with photos — we work on these lifts every week and can usually confirm fit from a picture and the lift's serial faster than you can dig through a parts diagram.

Why buy your Rotary arm restraint gear from Auto Lift Services

We install, inspect, and repair Rotary lifts every week — the ALS-7545-17 is a part we handle in the shop, not a random SKU we drop-ship. The phone answers if you have a question mid-install — call 800-674-9302 — and every part ships genuine, no aftermarket substitution unless you ask for it.