Farmall Cub

Why is the clutch brake needed at all on the 154 and 185 models?
My gear drive cub cadets don't have one and neither does my 184. If you use the regular brakes
like you're supposed to, stopping the tractor before shifting, and removed the clutch brake altogether would it really hurt anything?

Bob,
On the 154 and 185 design, the mass of the flywheel is located AFTER the clutch/pressure plate release assembly. With this type of design the inertial energy that is stored in the flywheel make the transmission input shaft of the transmission keep right on spinning for quite a while even though the clutch assembly has disconnected the transmission from the rotating engine - thus the gears in the transmission will grind until the flywheel spins down. The clutch brake stops the flywheel spin down sooner so that when you put the transmission into gear, the gears don't grind.
NJDale

Yea, the intertia on the flywheel and driveshaft along with the PTO components is much greater in the lo-boy, and the thing will just keep spinning. Trust me. Loosen it up and give it a try. You cannot shift gears at all because the driveshaft will just keep turning. It's there for a reason, don't take it out!

On the 184, the driveline is different because of the way the electric PTO is setup, and without all of the extra stuff turning, it was not needed.

On the 184, the drive clutch was moved back to the engine flywheel, so there is no spinning flywheel on the front of the transmission. The PTO set-ups have nothing to do with the need for the clutch brake.

The flywheel on all the tractors is in the same spot, on the engine. The DRIVEN disc is what is different and has some small amount of inertia. That along with a real ball bearing throwout bearing is the need for the clutch brake. Big trucks had clutch brakes in the past and maybe still do to slow the transmission input shaft so you did not have to wait as long to upshift.

The offset cubs also have a type of clutch brake, it's called graphite. The graphite throwout bearing has a fair amount of friction which slows the input shaft.

The part normally considered the "driven disk" of a clutch is on the drive shaft from the engine and is constantly turning at engine speed. The pressure plate assembly, which on this tractor includes the assembly usually considered a pressure plate and a second plate that pinches against the opposite side of the disk, serving the purpose usually done by the engine flywheel. This pressure plate assembly is almost all the rotating mass of the clutch and produces much more than "some small amount of inertia".

The graphite throwout bearing of an offset Cub applies pressure to the fingers on the pressure plate. This pressure plate rotates with the engine when the clutch is disengaged, having absolutely no effect as a clutch brake.

I have seen the term "Driven disc" used as I have used it. The flywheel is still on the engine, the pressure plate and friction disc are the same idea. The difference in a 154/185 clutch is the disc on the transmission input shaft and this is what I have seen as the "driven disc". It is what is driven by the friction disc. You could argue that the pressure plate is also driven by the friction disc and could also be called the driven disc but it already has a good name.

I can stop the driven disc with my hand and my baby soft skin, that is minimal inertia to me. However, inertia is not the best word, I should have used the term "momentum".

I was thinking backward about the graphite effects, completely wrong.

When I was a resident my fellow resident looked like George Clooney, I look like quasimodo. I got blamed for everything I did wrong, which was quite alot, but also got blamed for all the wrongs commited by my fellow resident. As a joke, some of the staff gave me a plastic human head that when yelled at, would respond with a few different responses. "I don't deserve to live" and "Its all my fault, I am a disease" were the two I can remember.

Mea culpa, Mea culpa, Mea maxima culpa

Or

EGO sum a morbus


Brings back memories.