Knowing the basics of how the brakes work is just one of those things any ATV owner should learn. This knowledge makes troubleshooting a lot easier when they do not work properly. You are also better able to maintain and keep the brakes sharp at all times.
Be aware that there has been quite a lot of variations of ATV brake systems throughout the years. The types described in this post will cover most types, but not all of them.
So how do ATV brakes work? ATVs use either disc brakes, drum brakes, or a combination of these two systems.
When the rider of an ATV with disc brakes activates the hand lever or foot pedal, brake fluid is being squeezed through the brake lines, activating the brake piston. This, in turn, pushes the brake pad against the brake disk or brake drum, creating friction.
On bikes with drum brakes, pulling the brake lever activates a steel cable that forces the brake shoes outwards against the inside of the brake drum.
Disc brake system (hydraulic braking system)
How hand-lever operated disc brakes works
The brake system consists of these basic components that all work together:
The rider pulls or squeezes the lever against the handlebar to operate the brakes. Pulling the lever will generally activate the brakes on all four wheels of the bike.
Next to the hand lever on the handlebar, you find the master cylinder. This consists of a small reservoir containing brake fluid and a small piston that works as a hydraulic actuator.
When the hand lever is activated, the small piston pushes brake fluid down the brake line, making it a hydraulic system.
The reservoir should have a gauge to tell the current level of fluid inside. On bikes with the “eye” style indicator on top of the reservoir, a dark center usually means that the reservoir is full. A white center indicates low levels of fluid.
Consult your owner’s manual to learn how to check the level on your specific bike. Make sure it is above the minimum at all times, but do not overfill either. Doing so may cause brake drag or brake lock-up.
The brake line is a pipe or tube transferring brake fluid from the master cylinder to the caliper on each wheel. The line needs to withstand high pressures and consist of flexible lines or solid steel or copper pipes.
The hydraulic fluid is what makes the whole system work. It’s important to use the right type of fluid for your bike, usually DOT 3 or DOT 4. Notice that if just a tiny amount of air gets into the system, the brakes will not function properly.
On each wheel hub, you’ll find a brake caliper. The caliper is a metal housing containing one or more pistons. It also has the job of keeping the brake pads in place.
Each wheel has a brake disc that is directly connected to- and spins at the same speed as the wheel. When the brake fluid reaches the piston inside the caliper, the piston is being pushed against the brake pad, which in turn, is being pushed against the brake disc.
The brake pad is made of a material that can handle the friction this creates, making the wheel spin slower.
Hand lever operated disc brakes activate the brake calipers either on all four wheels. Or they activate only on the two front wheels together with one of the rear wheels.
The latter option is true on bikes that rely on the rear diff to have brakes on both rear wheels. Thus needing a caliper on only one of them.
The pressure on all calipers is equal as there is no proportioning valve like you would find on most cars.
How foot pedal operated disc brakes work
Many bikes also feature a foot pedal in addition to the hand lever. On bikes fitted with just disc brakes on all four wheels, this pedal basically works just the same way as the hand lever.
But there are a few key differences.
It does have its own master cylinder that pushes brake fluid to the calipers, as described above. It might, however, have its brake fluid reservoir located somewhere else on the bike.
On a Polaris Sportsman, it is located under the front rack.
Another key difference is that the foot pedal will not operate the front brakes on all bikes. On some, it will only operate the rear. The master cylinder on the foot pedal will not be connected to the front calipers on these bikes.
The most common setup on newer bikes is one caliper on each wheel. The hand lever will operate all calipers, while the foot pedal will operate just the rear calipers.
But there are some variations out there.
Some older bikes have their own separate caliper (trailing) for the foot brake, usually fitted on one of the rear wheels. And even on some newer bikes, you will only find one single caliper fitted on one of the rear wheels.
Bikes set up this way, with a caliper just on one of the rear wheels, will likely have a locked rear diff, effectively making both wheels brake when you step on the pedal.
It would be best if you learned how your specific bike’s brakes work because mistakingly believing you will get full brake power only from using your foot pedal can be a fatal mistake.
If you suddenly need to stop at fast as possible, activating just the rear wheel brakes will on these bikes give a much longer stopping distance than when all wheels are braking.
To learn how your bike is designed, you can inspect where the foot pedal master cylinder’s brake lines go.
Or, you can test the bike at slower speeds on an open gravel lot, with no risk of smashing into others.
If the rear end starts sliding to either side when you use the foot pedal but not when you’re using the hand lever, you know that the foot pedal likely only activates the rear brakes.
Drum brake systems
ATVs that do not have disc brakes will likely have drum brakes. Drum brakes are more common on cheaper or older models. You may also run into models with drum brakes on the rear wheels but disc brakes on the front.
Drum brake systems are fairly simple designs, but they are generally not as effective as disc brakes.
These are the components they are made up of and how they work together:
Hand lever or foot pedal
Operates the same way as on disc brake systems.
Connected to the hand lever or foot pedal, you’ll find a brake cable. The cable consists of a thin steel wire inside a protective housing where it can slide freely back and forth as you operate the brake lever.
The brake hub is fitted where the suspension meets the wheel and spins freely at the same speed which the wheel turns. The drum is all metal, and inside, it is shaped like the inside of a drum, hence the name, drum brakes. The inside steel walls of the hub serve the same purpose as the discs on the disc brakes. They create friction when brake pads are pushed against them.
Inside the brake drum, you’ll find the brake shoe, which works similar to how brake pads work on disc brakes. Two brake shoes in each hub are the most common setup.
The brake cable is connected to a lever on the brake hub, that when pulled, forces the brake shoes outward against the steel drum, creating the braking effect.
Small springs connected directly to the shoes then retract them away from the drum when you release the brake lever or foot pedal.
Most bikes are fitted with a parking brake system to help keep the bike in a stationary position whenever parked.
I always use it when parking in steep hills to help the bike’s transmission slip more easily in and out of PARK.
While on many cars, you usually have a separate brake wire that bypasses the hydraulic braking system, this is not the case on ATVs.
Usually, the parking brake works by locking the hand lever in the activated position. This utilizes the bike’s primary braking system as a parking brake. It will keep the brakes on all four wheels constantly activated until the brake is released.
- To activate the parking brake, pull the brake lever all the way against the handlebar. While holding the lever in this position with one hand, use your free hand to flip the locking mechanism, preventing the lever from retracting when you release your grip.
- To release the parking brake, squeeze the hand lever and release the locking mechanism.
The locking mechanism will look a bit different from model to model but works by the same principles. On my Polaris, you find a two-step switch where you can choose how much force you wish to apply.
You may find a more simple hand brake locking mechanism like the one I have on my old Lynx snowmobile on older bikes.
ABS (Anti-Lock Braking System)
As Can-Am recently introduced ABS braking systems to the ATV world, I’ll end this post with a few lines on the basics of how this system works.
An ABS system basically consists of the same components as a conventional hydraulic brake system with some additional anti-locking components.
The additional components are a hydraulic electronic control unit (called ECU) plus a few hydraulic pressure sensors and speed sensors.
The sensors detect how the wheels behave in different braking situations and send it’s signal to the ECU.
The ECU is the brains of the operation, and based on the sensors’ signals, it calculates and adjusts how much braking force that needs to go to each caliper for optimal stopping power.
This all happens instantly and much faster and more precise than any rider could achieve on non-ABS systems.
What to do when ATV brake pads are squealing?
ATV brakes squealing may be because of dirt on the brake pads and discs. Try cleaning them with brake cleaner. Installing an anti-squeal sticker made from aluminum will also work.