HBB - How often does the motor run?

[erad]

I tried in the top of the Gen 3 forum, but like me, most people probably don't read the top entry in tat forum, so here goes here.

The brake pads on my vehicles typically last 300 to 400000 km - I rarely use the brakes the way I drive, and whee I drive. This also means that I rarely press the brake pedal. Typically the minimum trip on my vehicles is well over 100 km, and usually in very light traffic. So the brakes don't get used. How much will the motor in the HBB run compared to the average? If the HBB motor only gets used when I press on the brake pedal, theoretically I should never have to replace the motor or the unit itself. However, if the motor is running all the time, I would expect it to wear out in a finite time. Which is it - motor on all the time or only when the brakes are being used?

[Pajshomoneroguntero]

I think it is activated by a pressure switch so perhaps every few brake applications dependent a bit on the severity of application.

[NFT5]

Neither. The pump motor pressurises the system then turns off, restarting only when pressure drops below the preset limit.


I don't think that you'll need to worry too much about it wearing out.

[erad]

Thanks for those replies. I guessed as much, but would like confirmation. I imagine the HBB pump would only come into action when the pressure drops ie if you use the brakes or have a leak in the system up to the brake pedal. The system must be similar to my old Citroen - it used the high pressure oil from the suspension for the brakes. Brilliant system - the front and rear systems were separated, and activated via a plate. The rear suspension pressure activated a small piston which moved the pivot point on the plate, so if the car had a heavy load in the rear, the rear brakes got more pressure. Thus the rear brakes had an inbuilt load compensation. If only all cars had such a system.

[sharkcaver]

As NFT5 says, it comes on with pressure drop. It doesn't need pedal activation to produce that drop. Open your bonnet, turn ignition on and listen to how often it recharges itself without touching the brakes. Its a regular cycle.

You are over thinking it. You are not going to flog it out by using it and your not going to save it by not using it. Anyway, they are brakes, you have to use it.

Sure, there has been a few reported cases where the HBB has failed after some mileage, but I think there are plenty more disastrous things on the gen 3 to worry about before that.

[benckj]

Having the HBB motor fail with 97km on the clock is very disastrous to say the least. It wouldn’t be so bad if it was simply a power assist issue but to loose all brakes makes mobility impossible. Even when mine failed intermittently the drive across my small town using the handbrake was frightful.