3579487C95 | Genuine International® Hydraulic Unit Park Brake (SAHR)

HUPBs are typically spring-applied, hydraulic-released (SAHR):
-Springs apply the brake by default
-Hydraulic pressure is needed to release it
So if:
-The engine shuts off
-Hydraulic pressure drops
-A line fails

The brake automatically engages
This is critical in heavy vehicles where runaway movement is dangerous.

2. Parking brake for heavy loads
On large trucks, buses, or machinery:
-Traditional cable parking brakes aren’t strong enough
-HUPBs provide high holding force using internal springs

Used on:
-International DuraStar 4300
-Ford F-750
-Construction equipment and industrial machines

3. Emergency braking backup

If the primary braking system fails:
-The HUPB can act as a secondary/emergency brake
-It engages automatically when pressure is lost

4. Integration with hydraulic systems

Many medium-duty vehicles use hydraulic service brakes (not air brakes):
-The HUPB integrates directly into that system
-Makes it ideal for fleets that don’t use full air brake setups

-Vehicle won’t move even after you disengage the parking brake
-Feels “locked” or dragging

Likely causes:
-Low or no hydraulic pressure
-Faulty solenoid/valve
-Internal piston or seal failure

2. Brake won’t hold (vehicle creeps)
-Vehicle rolls slightly when parked
-Can’t hold on inclines

Likely causes:
-Weak or broken internal springs
-Worn brake discs or components
-Internal leakage reducing clamp force

3. Slow or delayed release
-Takes a few seconds (or longer) before the vehicle can move

Likely causes:
-Restricted hydraulic lines
-Contaminated fluid
-Failing internal seals

4. Hydraulic fluid leaks
-Visible oil around the brake unit
-Dropping fluid levels in reservoir

Likely causes:
-Worn seals or O-rings
-Cracked housing or fittings

This is a serious one—loss of pressure can cause the brake to engage unexpectedly.

5. Overheating or burning smell
-Brake stays partially engaged while driving
-Excess heat near the unit

Likely causes:
-Brake not fully releasing
-Internal drag

6. Warning lights or fault codes
-Dash warnings related to brake or hydraulic system

Likely causes:
-Pressure sensor issues
-Electronic control faults

7. Unusual noises
-Grinding, squealing, or clunking

Likely causes:
-Internal mechanical wear
-Damaged components inside the brake pack