5396-MA15511 | Genuine Haldex® Maxibrake HR Series Spring Brake Chamber

1. Provide Parking Brake Function

Inside the chamber is a very powerful spring.

• When air pressure is removed → The spring expands → Brakes apply

• This holds the vehicle in place when parked

This replaces a traditional handbrake system found in smaller vehicles.

2. Provide Emergency (Fail-Safe) Braking

Air brake systems depend on compressed air.

If:

• There is a major air leak

• Air pressure drops too low

• The system fails

The spring automatically applies the brakes.

This prevents runaway trucks.

3. Assist in Service Braking

The spring brake chamber also contains a service brake section.

When the driver presses the brake pedal:

• Air pressure enters the service chamber

• The pushrod moves

• Brakes apply normally

So it handles both:

• Normal braking

• Parking/emergency braking

1. Air Leaks (Most Common)

• Hissing sound near wheel area

• Air pressure drops when parked

• Air compressor runs more often

This usually means:

• Ruptured diaphragm

• Cracked housing

• Failed internal seal

2. Parking Brake Won’t Release

• Truck won’t move after releasing parking brake

• One wheel dragging

• Burning brake smell

Could be:

• Broken internal spring

• Seized pushrod

• Internal mechanical failure

3. Brakes Drag While Driving

• Truck feels sluggish

• Overheating wheel or drum

• Uneven tire wear

The spring side may not be fully releasing.

4. Weak Parking Brake

• Vehicle rolls slightly when parked

• Doesn’t hold well on a hill

May indicate:

• Weak or damaged internal spring

• Excessive pushrod stroke

• Brake adjustment issues

5. Excessive Pushrod Travel

• Pushrod extends too far when brakes are applied

• Fails DOT inspection stroke measurement

This can indicate:

• Worn brake components

• Internal chamber issue

6. Visible Physical Damage

• Rusted or dented chamber

• Broken clamp band

• Corrosion around housing

Severe rust can weaken the chamber housing.

7. Sudden Lock-Up While Driving (Serious)

If air pressure drops suddenly:

• Spring brake may apply automatically

• Truck may decelerate rapidly

This is a safety feature, but if it happens unexpectedly, the chamber or air system may be failing.