Guide
How does a treadmill work: motor, belt, deck and rollers
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In short
An electric motor at the front turns the front roller, usually through a short drive belt. The front roller pulls a long running belt around a flat deck and over a rear roller. You walk on the top of the belt, which slides over the lubricated deck. A controller sets motor speed from the console or remote, and powered incline models add a second motor to raise the front.
Products for this job
Compare all 7 productsKALWOL 4-in-1: 10% incline, 40 dB or less, 160 kg
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A treadmill looks simple: a belt goes round and you walk on it. Knowing what is underneath helps you choose a machine, keep it running smoothly and understand what has gone wrong when it starts to squeak, slip or stop. Walking pads and folding treadmills use the same basic parts, arranged differently. This explainer goes through each part in turn, what it does, and what care it usually needs.
The main parts at a glance
Most motorised treadmills and walking pads share these parts. Details vary between models; your manual has a parts diagram.
| Part | What it does | Usual care |
|---|---|---|
| Motor | Turns the front roller | Keep the motor area free of dust |
| Drive belt | Links motor and front roller on many machines | Checked by a technician if it slips |
| Front roller | Drives the running belt | Rarely needs attention |
| Rear roller | Idler; adjusts tension and tracking | Tension bolts adjusted as needed |
| Running belt | The surface you walk on | Clean, tension, centre, replace when worn |
| Deck | Flat board under the belt | Lubricate as the manual says |
| Shock absorbers | Soften the deck under each step | Check for wear |
| Controller and console | Set speed, read sensors | Keep dry |
| Safety key | Cuts the motor when pulled | Use every time |
The motor and controller
Home treadmills mostly use DC motors, and many newer walking pads use brushless DC motors, which are generally quieter and need less maintenance. The motor sits under a cover at the front. A controller board takes your speed setting from the console, remote or app and adjusts the power to the motor, using a speed sensor to keep the belt at the set speed as you step on it.
Motor ratings are given in horsepower, but the figures are not always comparable between makers. Our article on treadmill motor HP explains what to look for, and brushless vs brushed motors covers the motor types.
Rollers, belt and deck
The running belt is a continuous loop. The front roller, driven by the motor, pulls the top of the belt backwards under your feet. The rear roller is an idler; it turns freely and is mounted on two bolts that set the belt's tension and tracking. Turning them adjusts how tight the belt is and whether it runs centred. See how to adjust a treadmill belt.
Between the rollers, the belt slides over a flat deck. The deck supports your weight, and a thin layer of silicone or wax lets the belt glide. When that layer wears, friction rises, the motor works harder and the belt may squeak or judder. Our lubrication guide and silicone vs wax article explain the care involved.
Cushioning, incline and folding
Under the deck, rubber elastomers or other shock absorbers soften each footfall. Some belts also have cushioning layers. See treadmill cushioning explained.
Treadmills with powered incline have a second motor, usually a linear actuator, that pushes the front of the deck up. Manual incline uses a lever or feet instead. Folding treadmills add a hinge and often a gas strut to help lift the deck. Each of these adds parts that can need attention over time; see do all treadmills have an incline.
How walking pads differ from treadmills
A walking pad uses the same principle with a lower, simpler layout. The motor is often a compact unit within a slim front cover, the deck is shorter, and there is usually no upright console. Control comes from a remote or app, and some pads have automatic modes that use sensors to adjust speed by where you stand on the belt. See what is a walking pad.
Knowing the parts makes it easier to compare listings. Our walking pad guide and folding treadmill guide compare models on belt size, motor and speed.
Frequently asked questions
How does a treadmill work? A motor turns the front roller, which pulls a belt around a lubricated deck and over a rear roller. A controller sets the speed.
How do walking pads work? The same way, with a lower, simpler build and a remote instead of an upright console.
Why does a treadmill need lubricating? The belt slides over the deck. Lubricant reduces friction so the belt glides and the motor does not overwork.
What does the rear roller do? It is an idler roller whose bolts set belt tension and tracking.
What you need
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KALWOL 4-in-1: 10% incline, 40 dB or less, 160 kg
- Check price on AmazonAffiliate link
UMAY treadmill: 15% auto incline, 12 km/h, 180 kg