F00E590067 | Genuine Wabco® Hydraulic Pump W/Motor

• International (Navistar)
  • DuraStar (4000 Series)
  • WorkStar
  • TerraStar
  • IC Bus models
• Freightliner
  • Business Class M2 (selected hydraulic brake configurations)
• Hino
  • 155
  • 195
  • 238
  • 258
  • 268
  • 338 (selected models)
• Isuzu
  • NPR
  • NQR
  • NRR (hydraulic brake models)
• Blue Bird school buses (selected hydraulic brake systems)
• Other medium-duty trucks using Bosch/Bendix HydroMax or Electro-Hydraulic Brake Assist systems.

1. Provide power

• The motor (electric or engine-driven) turns on

• Supplies rotational energy

2. Drive the pump

• The motor spins the hydraulic pump

• This is what actually moves the fluid

3. Move hydraulic fluid

• Fluid is pulled from a reservoir

• Then pushed through the system

4. Create pressure

• The pump forces fluid into tight spaces

• This builds high pressure needed to do work

5. Perform mechanical work

That pressure is used to:

• Move pistons

• Apply braking force

• Lift heavy loads

• Operate machinery

6. Maintain system operation

• Keeps fluid circulating

• Ensures consistent performance

1. Unusual noise (first warning)

• Whining, buzzing, or grinding sound

• Often gets louder when the system is under load

• In ABS systems, you may hear it during hard braking tied to the anti-lock braking system

2. Slow or weak performance

• System feels sluggish:

  • Slow brake pressure recovery (ABS)

  • Slow lifting or movement (equipment)

• Indicates the pump isn’t building pressure efficiently

3. Intermittent operation

• Works sometimes, then stops

• May cut in and out due to:

  • Worn motor brushes (electric motors)

  • Internal electrical faults

4. Overheating

• Motor gets unusually hot

• May produce a burning smell

• Caused by:

  • Internal friction

  • Electrical resistance

5. Blown fuse or electrical issues

• Motor may:

  • Trip circuits

  • Blow fuses repeatedly

• Suggests internal short or overload

6. Low or no hydraulic pressure

• System can’t build pressure

• Symptoms:

  • Weak braking assist

  • No ABS pressure recovery

  • Equipment won’t move properly

7. ABS or system warning lights

(In vehicles)

• ABS light comes on

• System disables due to pump failure

• Often confused with modulator failure

8. Complete failure (no operation)

• Motor doesn’t run at all

• No sound, no pressure, no response

• System relying on it stops working completely