What Is Spring Brake
What Is Spring Brake This comprehensive article seeks to demystify spring brakes, shedding light on their purpose, operation, subsystems, and functions.
Understanding Spring Brakes
Spring brakes serve the critical function of engaging automatically after a vehicle is parked or in the unfortunate event of a service brake failure. These brakes are designed to enhance safety and prevent vehicular accidents.
Disabling the Spring-Brake Chamber
In the event of an emergency, a technician can employ a caging bolt or another mechanism to compress or “cage” the spring within the spring brake chamber. This action is essential for moving a vehicle under such dire circumstances. Temporarily disabling the spring brake chamber through manual caging renders parking and emergency braking impossible.
When a spring brake chamber is disabled or caged, it becomes visually evident as the caging bolt or alternative mechanism protrudes, signifying its deactivated state. Should drivers encounter a disabled spring brake chamber, immediate vehicle inspection is imperative.
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Spring Brakes for Emergency Braking and Parking
Most vehicles equipped with air brakes boast an emergency braking system that comes into play when the service brake system experiences a malfunction. This system relies on spring brakes as the parking brake mechanism. Spring brakes function distinctively compared to service brakes; they operate independently of air pressure for application and release. Instead, they harness the power of a large coil spring to engage and maintain brakes in the applied position. Spring brakes are modular and can be integrated with separate brake chambers. When a spring brake component is added to a service brake chamber, the resulting unit is referred to as a spring brake chamber.
Before spring brakes can be compressed or “caged,” they necessitate a minimum air pressure supply of 414 kPa (60 psi) within the chamber. In the absence of this pressure, spring brakes engage automatically. However, many vehicles still permit limited operation even when spring brakes are engaged due to the full-service brake application.
Ensuring adequate air pressure within the air brake system before driving is essential to prevent inadvertent activation of spring brakes. The substantial coil spring within the spring brake chamber is under significant tension and, if tampered with, damaged, or corroded, can trigger sudden and forceful movement of brake chamber components.
The Mechanics of Spring Brakes
When the brake pedal is depressed, brake fluid is directed through the master cylinder, passing through the ABS control module. This fluid flows to the calipers, exerting pressure to engage the pads against the rotors. Notably, in contrast to passenger cars, heavy trucks employ air pressure to activate braking power. Herein lies the significance of spring brakes, predominantly used for parking brakes, situated on the rear axle of heavy trucks.
To disengage the parking brake, pressure is applied to the spring side. The parking brakes become active as the spring is decompressed, typically requiring a force of 20 lbs.
During vehicle operation, air pressure keeps the springs in check. If a leak causes a drop in air pressure, the springs automatically activate the brakes. This fail-safe mechanism ensures brake engagement in the event of air pressure system failure.
Vital Considerations
It is paramount to note that full-service brake application does not provide sufficient braking power, necessitating operation with spring brakes engaged. To prevent this scenario, maintaining adequate air pressure in the brake system, typically around 60 psi, is crucial.
This safety protocol was established to address past challenges wherein trucks with depleted air pressure struggled to come to a controlled stop.
Read More : What Is A Dual Air Brake System
Frequently Asked Questions (FAQs)
1. Do converter dollies have spring brakes?
- Yes, converter dollies are equipped with spring brakes.
2. How do spring brakes address the problem?
- In the event of reduced air pressure, the spring within the brake chamber decompresses, affording the driver more reaction time. An alarm will also sound if pressure falls below 60 lbs.
- Spring brakes consist of two chambers: one to release the spring and one to activate braking force. In the event of a sudden pressure loss, the powerful spring engages the brakes, ensuring vehicle control.
- The cage bolt can be employed if the vehicle needs to be moved without air pressure. Once the vehicle is appropriately positioned, the bolt should be changed or removed.