Newbie with air brake question

[karitoki]

I'm the second owner of a 1994 Coachmen Santara diesel pusher. The coach has 14,800 miles on it, and had $1,800.00 in front end brake work done a month before I bought it. My question is: Is it normal to have to press the brake pedal nearly to the floor to engage the brakes? Doesn't seem right to me. When the brakes do engage they stop fine; I was just expecting an earlier engagement.

Thanks in advance!

 

[TJ&LadyDi]

It is hard to generalize across brand/model lines, but that doesn't sound right to me. Both of our coaches with air brakes engaged with only a small amount of pedal travel. I would have it looked at. It may be a simple linkage adjustment or, improper brake pad/shoe adjustment.

TJ

 

[Chuggs]

It would be nice to know...do you have automatic slack adjusters?

Unless someone has mechanically changed the peddle to treadle valve linkage... the first thing to check after that is brake servo adjustment. Most of the bendix units in today’s coaches have automatic slack adjusters built-in... If yours either doesn’t have this feature, or it is impaired and hasn’t performed it’s job properly...the engagement of the brakes will be negatively impacted.

I‘m sure other factors can come into play...but it would be worth getting the system checked by a shop that works on these common air brake systems. They can measure the throw on the brake servo as it’s actuated...and check to see if your slack adjusters are working or in need of cleaning or replacement.

 

[MapNerd]

Please elaborate on the following statement and do not drive the coach again until doing so:

When the brakes do engage they stop fine

Do your brakes not always engage when you depress the brake pedal? If not, I would not say that is normal behavior.

 

[karitoki]

Please elaborate on the following statement and do not drive the coach again until doing so:

Do your brakes not always engage when you depress the brake pedal? If not, I would not say that is normal behavior.
View attachment 3876

What I meant by that is the coach stops completely when the brake pedal is almost to the floor. And yes, I have no intentions of driving this until it's resolved.

 

[karitoki]

It is hard to generalize across brand/model lines, but that doesn't sound right to me. Both of our coaches with air brakes engaged with only a small amount of pedal travel. I would have it looked at. It may be a simple linkage adjustment or, improper brake pad/shoe adjustment.

TJ

Thanks! I have a mobile diesel mechanic coming over this Saturday to check it over. I'll have this at the top of the list of things to do!

 

[karitoki]

It would be nice to know...do you have automatic slack adjusters?

Unless someone has mechanically changed the peddle to treadle valve linkage... the first thing to check after that is brake servo adjustment. Most of the bendix units in today’s coaches have automatic slack adjusters built-in... If yours either doesn’t have this feature, or it is impaired and hasn’t performed it’s job properly...the engagement of the brakes will be negatively impacted.

I‘m sure other factors can come into play...but it would be worth getting the system checked by a shop that works on these common air brake systems. They can measure the throw on the brake servo as it’s actuated...and check to see if your slack adjusters are working or in need of cleaning or replacement.

Thanks! I popped the "hood" and saw that there's a brake fluid reservoir there. I cleaned the exterior and opened it up and found it full with clean fluid. How does the hydraulic equipment work with the air system?

 

[Chuggs]

Thanks! I popped the "hood" and saw that there's a brake fluid reservoir there. I cleaned the exterior and opened it up and found it full with clean fluid. How does the hydraulic equipment work with the air system?

So...why title your thread "Newbie with airbrake question"?????

No, my dad’s Southwind Diesel Pusher, like yours, has hydraulic brakes. You're just figuring this out???

- brake lines
- fresh dry fluid
- pads, drums, rotors
- adjusters
- Master cylinder
- Booster (vacuum or hydraulic “hydro-boost”)

Something there should improve NON-airbrake performance.

 

[karitoki]

So...why title your thread "Newbie with airbrake question"?????

No, my dad’s Southwind Diesel Pusher, like yours, has hydraulic brakes. You're just figuring this out???

- brake lines
- fresh dry fluid
- pads, drums, rotors
- adjusters
- Master cylinder
- Booster (vacuum or hydraulic “hydro-boost”)

Something there should improve NON-airbrake performance.

The rig has air brakes, no question. Yellow parking brake knob, red and green air lines to the calipers, air sound when pressing the brake, the whole deal. That’s the reason for the thread title.

 

[Chuggs]

The rig has air brakes, no question. Yellow parking brake knob, red and green air lines to the calipers, air sound when pressing the brake, the whole deal. That’s the reason for the thread title.

I’m Confused...my Air Brake coach doesn’t have a brake fluid reservoir.

Your air lines go to the brake servos. I guess you could have a different type of metering device. My treadle valve is all air. Maybe you have a hydraulic actuation of your air trade valve. I’ve not seen this before,,,but I’m not a chassis expert.