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2026
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07
Assisted braking isn't foolproof; remember to use caution or avoid it in certain situations.
In recent years, auxiliary braking devices have become widely used in domestic heavy-duty trucks, and more and more truck drivers are starting to understand and appreciate how these devices help with safe driving.
But the editor found that quite a few truck enthusiasts still have some 'misunderstandings' about using auxiliary braking systems. For example, people often ask: 'Can auxiliary brakes be used on icy or snowy roads?' The answer is simple: on extreme road conditions like ice and snow, auxiliary braking should definitely be used with caution or not at all!
● What are auxiliary braking devices?
First, we need to clarify a concept: what exactly is an auxiliary brake? What types of technology are there? Systems we often talk about like ABS, ESP, EBD, and ABS EBD aren’t technically auxiliary braking devices. These functions are part of active braking assistance systems, so we call them electronic assistance systems (driver assistance systems).
So what exactly is an auxiliary braking device? Simply put, unlike our traditional brakes, auxiliary braking devices help the car slow down. The common types of auxiliary braking devices we see today mainly include exhaust brakes, engine brakes, and retarders (such as electric or hydraulic retarders).
● Auxiliary brakes aren’t万能—Use with caution or not at all on icy or snowy roads
Although truck safety technology is quite developed now, these technologies are not "invincible." Active safety systems like ABS, EBD, and auxiliary braking devices all have specific conditions and scenarios where they work best—they can't guarantee truck drivers' "absolute safety." Skilled driving and cautious handling are still the "top priority" for safe truck operation.
Exhaust brake: Normally, the exhaust brake valve is installed on the engine exhaust manifold. By closing the engine's exhaust passage, the pistons in the exhaust stroke encounter reverse gas pressure, slowing down the engine's operation and creating a braking effect to help control the vehicle's speed.
On icy and snowy roads, if you're driving just the truck tractor, you can use the exhaust brake cautiously depending on the vehicle's condition. But if you’re driving with a trailer, using the exhaust brake will slow down the tractor and can easily cause the trailer to push the tractor. So on icy and snowy roads, definitely avoid using the exhaust brake when you have a trailer attached.
Engine braking: Lift your foot off the accelerator to use the compression resistance from the engine’s compression stroke, along with internal friction and intake/exhaust resistance, to create a braking effect on the drive wheels.
Currently, the engine brakes on the market mainly include the Jake engine brake, the iBrake system used by Foton Cummins, and FAW's independently developed FCB system. Their braking torque is much higher than that of ordinary exhaust brakes, so you need to be careful when driving on wet or snowy roads. On black ice, using engine braking is strictly prohibited because the risk of jackknifing, skidding, or tipping over is very high.
Retarder braking: Retarders can be classified by type into electric eddy current retarders and hydraulic retarders, by medium into oil-medium retarders and water-medium retarders, and by installation method into series, parallel, or independent retarders. I won’t go into details here.
An electric eddy current retarder is installed between the vehicle’s drive axle and transmission and achieves contactless braking through electromagnetic induction.
Simply put, a hydraulic retarder is a device that uses the torque generated by the interaction between the fluid or water and the stator and rotor to provide continuous, wear-free braking, which helps slow down the vehicle.
Because the braking torque of the hydraulic retarder is higher than that of engine compression braking and exhaust braking. In extremely harsh weather, you shouldn’t suddenly switch it to full power; sudden excessive deceleration can easily cause vehicle rollover or jackknifing. Although modern vehicles are linked with ABS or AEB systems, which will deactivate the hydraulic retarder if wheel slip is detected, it’s still safer to use the retarder cautiously on slippery roads. On icy or snowy roads, especially on black ice, using the retarder is strictly prohibited.
● Editor’s Note
Even though various safety technologies today have gradually reduced the likelihood of danger while driving, as mentioned earlier, these auxiliary braking systems are not 'invincible.' Especially in rainy, snowy, slippery, or black ice conditions, it’s important to be cautious or even avoid using them. In extreme road situations, it’s best to adopt a careful low-speed driving approach or even stop driving. After all, safety is the top priority in our driving careers.
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