Not exactly... agree, the lack of the butterfly valve on the intake side prevents higher vacuum (that would be there in the intake port if the intake path was more closed by the butterfly) but the intake stroke still creates a lot of vacuum and pulls in the air on a diesel.
Jake brakes makes a very large air compressor out of the engine. Some diesel Jake brake systems are augmented by a butterfly in the exhaust which increases back pressure for greater braking. One thing NOT clear to me is whether fuel is still being injected while Jake braking is used. It would not ignite (because of the reduced compression) but would be wasteful of fuel and increase crud in the exhaust I would think.
I think I paid $60 for an over run clutch to save on my PTO brake.
Sadly, that is the way it is. An over running coupler isn't all that expensive anyway and mist of my driven implements have one built into the driveline anyway. Only ones that don't are the bat wing and the 3 point shredder.
Notice I have a replacement next to the one I jacked up probably install it tomorrow and yes unfortunately the pto brake on my old 4150 has long been worn to non working status. Surprisingly when the coupler is attached it does not freewheel with or without anything hooked up to it I'm pretty sure eventually I'll have to split that old tractor for various reasons it's now pushing 5k hrs, When the time comes I'm looking at it as another learning experience
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I do not understand this conversation -- I use a MF 2660 which is a 2011 model & I would not call it ancient. Seems reasonably "modern" to me. There is no PTO brake to my knowledge and I have no idea why anyone would want one nor consider themselves 'modern' if they have one. So long as the PTO free-wheels when you take it out of gear and runs under power when engaged what else matters ? Why ? All tractors I have seen/driven since around 1970 work that way. The need for these "overrunning clutches" or shaft devices is that they allow the flywheel effect of attachments such as a bush hog to take place safely, not shove the tractor forward and not rip apart the PTO gears on the tractor if it is old and unprotected. I tore up a PTO gearbox on an old 1954 Massey Harris once using a bush hog and failed to realize the old MH PTO does not freewheel. What other issues are there?
Independant PTO have a clutch pack within the transmission.
I guess you know more about it than I do but I have never seen my PTO persist in turning after I put it out of gear (other than when some flywheel is involved like a bush hog) nor seen it suddenly stop turning when I put it out of gear (which would be evidence of a PTO brake.) So far, I conclude that whatever is going on is just fine with me and since I only put about 100hrs on it a year it will very likely outlast me anyway. Can't get excited about it.
I believe the L series of the 80s and early 90s aren't the most durable either in my experience my old 2850 had one previously installed not knowing much about them I almost removed it fortunately read up on them and left it. Pto brake still works on that old tractor I used that tractor for chopping and chipping before my 4150. so they do work to preserve the functionality of the pto brake like 5030 and other members say.
