Arm Restraints Explained: What They Do and Why They Matter

If you’ve ever wondered why a two-post lift has a little clip, chain, or ratchet strap running from one arm to the frame of the lift, this article on arm restraints explained is for you. Arm restraints are a required safety component on nearly every two-post lift built in the last few decades, and they exist for one simple reason: to keep the arms from swinging out from under a vehicle once it’s in the air. We install and service lifts all over Iowa, and we still run into shops with restraints that are broken, missing, or bypassed entirely. That’s a liability problem waiting to happen, and it’s an easy fix.

What Arm Restraints Actually Do

The core job of an arm restraint is mechanical, not electronic. On most two-post lifts, once you swing the arms under the vehicle’s pickup points and start raising it, the arms are held in position by friction and the load of the car itself. That’s usually enough under normal conditions, but if something shifts — a bad pad placement, an unexpected bump against the vehicle, or someone leaning on an arm while it’s loaded — an unrestrained arm can rotate out from under the car. With arm restraints explained simply: they’re the backup that keeps that from happening. A chain, cable, or strap connects the arm to a fixed point on the column or carriage, limiting how far it can swing once weight is applied.

This isn’t an optional accessory. Nearly every lift manufacturer we work with — Rotary, Challenger, BendPak — ships two-post lifts with arm restraints as a standard safety component, and ALI (Automotive Lift Institute) certification requires them on qualifying lifts. If a lift in your shop doesn’t have working restraints on all four arms, it’s not meeting the standard it was built to meet, full stop. We’ve seen technicians get hurt because a restraint was missing on just one arm, and it’s almost always because the original hardware got lost during a move or a rushed reinstall.

Common Types of Arm Restraint Hardware

Not every lift uses the same restraint hardware, and that’s where a lot of confusion comes from when people search for arm restraints explained online. Older Rotary lifts and many Challenger models use a simple chain-and-hook setup — a short length of chain bolted to the arm with a hook that catches a fixed pin on the carriage once the arm is swung into position. BendPak and Atlas lifts on the home and light-commercial side often use a similar chain design, sometimes with a spring-loaded latch instead of a hook for faster engagement.

Some heavier-duty and older lift models use a cable-and-clip restraint instead of chain, which does the same job but wears differently over time — the cable can fray at the swage point long before it looks obviously bad from a distance. Whatever style your lift uses, the restraint has to match the original manufacturer spec for length and attachment point. A restraint that’s too long defeats the purpose because it lets the arm travel too far before catching. We keep restraint kits on hand for Rotary, Challenger, and BendPak lifts specifically because so many shops call us after finding a broken one during a routine inspection.

Why Restraints Fail Over Time

Arm restraints take abuse that most shop owners don’t think about. Every time an arm swings in or out from under a vehicle, the restraint chain or cable gets yanked, twisted, and occasionally caught under a tire or dropped tool. Over years of daily use, links stretch, hooks bend open slightly, and cable strands start to separate near the crimp. None of that is visible from six feet away during a quick glance before opening the shop — it takes someone actually pulling on the restraint to feel whether it’s still tight.

We’ve also seen restraints get removed on purpose, which is worse than one wearing out. Sometimes a tech disconnects a restraint because it’s in the way of a certain vehicle’s frame contact point, plans to reconnect it, and never does. On a two-post lift, the arm restraint is not a suggestion — it’s the difference between an arm that stays put and one that can swing loose mid-job. If you’re doing your own annual lift inspection, physically pull on every restraint on every arm, not just a visual check from across the bay.

Inspecting Your Restraints the Right Way

A proper inspection means checking each of the four restraints individually, with the lift empty and the arms swung to a few different positions. Look at the attachment bolt on the arm side first — that’s a common failure point because it takes direct load every cycle. Then check the hook, latch, or clip on the carriage side for wear, deformation, or rust that’s eating into the metal. If you see any link in a chain restraint that looks stretched or oval-shaped compared to the others, replace the whole chain rather than one link.

Cable restraints need a slightly different look — run your fingers along the length near both ends, since that’s where fraying starts before it’s visible. If you feel any sharp strands poking out, that cable needs to come off the lift immediately. This is a five-minute check per lift, and it should be part of every shop’s monthly maintenance routine, not just the annual inspection some shops schedule with us.

Model-Specific Restraint Notes We Get Asked About

We get a steady stream of calls asking about restraint parts for specific lift models, and the hardware really does vary by design. If you’re running a Rotary SPO10 or VLE10, the restraint setup differs from what you’ll find on a Mohawk A-7 or a Challenger SL210 — attachment points, chain length, and even the direction of arm swing change what fits. We’ve written detailed breakdowns for several of these: check our notes on SPO10 arm restraints, VLE10 arm restraints, and SL210 arm restraints if you’re trying to match parts to your exact lift.

For Mohawk owners specifically, the A-7 has its own restraint geometry that doesn’t cross over with newer Rotary-branded lifts, even though the two companies share some parts history. We keep a full write-up on Mohawk A-7 arm restraints as well. When in doubt about which restraint kit fits your lift, send us the model and serial number and we’ll match it before you order — guessing on restraint hardware is how shops end up with parts that don’t actually fit the swing radius of their arms.

Replacing Restraints Without Downtime

Swapping out a worn arm restraint is one of the simpler repairs on a two-post lift, and most shops can do it without taking the lift fully out of service for more than an hour. The process usually involves unbolting the old restraint from the arm, removing the worn hook or clip from the carriage-side attachment, and bolting in the new kit matched to your model. We always recommend replacing restraints in full sets rather than one at a time — if one has worn out from years of the same use cycle, the others aren’t far behind.

If you’re not confident doing the swap yourself, our technicians handle this as part of routine lift service calls across Iowa, often bundling restraint replacement with a broader safety inspection so you’re not paying for a separate trip later. Whether you handle it in-house or have us come out, the goal is the same — arm restraints explained and working the way the manufacturer intended, on every arm, every time.