Pinion Brakes

[mckeeranger]

The first time I saw pinion brakes on a crawler, I asked a retired Ford chassis engineer what he thought, and he told me two things.

1. It would be illegal. Federal law requires the brakes be independent per wheel. Then he went on and on about surface area of the brake pads and the gear ratio of the differentials working in favor of the engine, but would work against pinion brakes, etc..

2. (Keep in mind we were talking about an M817, not M35) He said something like "It might slow you down enough to have time to pucker your a$$ before you drive through whatever it was that made you hit the brakes."

 

[OPCOM]

I would like to see a pinion brake video on a test track/strip with a major braking incident from 50-60 down to stop. I wonder if the rotor would glow bright orange or only dull orange. It's a nagging question. Inquiring Minds. I'd think about it as an extra "parking brake" but never as part of the braking system for driving.

 

[mudguppy]

OPCOM - check out monster truck footage; after long runs you can clearly see the pinion disc glowing bright orange. flames are also not uncommon. even though it isn't apples/apples give the speeds, rotating mass, and the 18:1 gearing in the axles, but the comparison is still there.

pinion brakes have a tremendous mechanical advantage over wheel brakes but suffer from heat generation due to high rotor speeds over a relatively small surface area. service life will suffer greatly.

 

[Uzaree]

OPCOM - check out monster truck footage; after long runs you can clearly see the pinion disc glowing bright orange. flames are also not uncommon. even though it isn't apples/apples give the speeds, rotating mass, and the 18:1 gearing in the axles, but the comparison is still there.

pinion brakes have a tremendous mechanical advantage over wheel brakes but suffer from heat generation due to high rotor speeds over a relatively small surface area. service life will suffer greatly.

And Monster Trucks arent locked at the axle either.

I think I'll just look into either keeping the drum or doing a 6 wheel disk brake setup.

 

[timothy1]

Why not keep the drum brakes and upgrade the rest to little more modern. Since you want to compare look at a over road semi. Carry massive loads and run drum brakes, just everything else to it is better then a m35 style to get there. Your after surface area, and clamping pressure. Drums have that. The week link is everything else before it gets to your drums.

 

[m16ty]

A lot of people in the automobile world have heard all their life "disc brakes are better than drum brakes". While you can argue this on cars and light trucks, in heavy trucks it's not the case. The main thing you look for in a brake to stop a heavy load is surface area.

I've got a 3/4 ton Dodge with rear drum brakes. A friend of mine has a Ford of the same vintage with rear disc brakes. His truck will stop just as well as mine will but he goes through 3 sets of rear brakes to my one.

 

[rattlecan6104]

A lot of people in the automobile world have heard all their life "disc brakes are better than drum brakes". While you can argue this on cars and light trucks, in heavy trucks it's not the case. The main thing you look for in a brake to stop a heavy load is surface area.

I've got a 3/4 ton Dodge with rear drum brakes. A friend of mine has a Ford of the same vintage with rear disc brakes. His truck will stop just as well as mine will but he goes through 3 sets of rear brakes to my one.

That never would have crossed my mind, good to know.