Catmando clutch operating instructional manual.

Well we shall see how this works. The age old question. Double clutch or not. Some guys have drove 75 years and never wore out a clutch or transmission because they shift like butter. Well that's debatable and most can not. I'll do my best to explain, while I'm not the best author.

Eaton fuller instructions indicate double clutching is proper shifting technique. CDL requirements require double clutching. But we need to dive deeper into this.

The reasons are much deeper than most see. The process of double clutching provides much more than simply wearing out a clutch. In a non synchronized transmission, you the driver are the one responsible to sync gears. Now imagine a clutch as fuse between a engine and trans, a safety. It is designed to wear out. So here is a few simple issues with floating gears. When you simply slip that out of gear and into gear with out clutch input.

With clutch engagement, the transmission and drive train are underload, regardless of rpm. When you depress pedal and disengage clutch the transmission is not under engine load. Non synchronized transmissions are not designed for shifting under load. So what happens, there is more force applied to all gears, mostly sliding clutches, main shafts, main gears. They have a tendency to bind, grind, rake. Now guys can do this very smooth with practice. I have seldomly seen many people that actually can. Meet alot that claim to. The gears are not built for load while gear change, the are only designed to have load while fully engaged. This accelerates wear on matting gears between gear splines, sliding clutches and main shaft. Extremely possible to twist mainshaft splines during a shift under load. Main shafts are straight cut splines with floating gears. Power flow is from input shaft main drive gear to counter shafts, to selected gear on main shaft. Locking main together creating output to aux. box to output shaft. But we shall go deeper. Torque is a twisting force that results in motion. We design bearings, parts to control torque, eliminate endplay. However must have some endplay to allow operation. Endplay is in engines, wheel ends, differentials, especially transmissions. The main shaft in a eaton fuller trans is floating. When you do not the disengage clutch, there is little to no endplay in shaft during gear change. Bound is the word I would use. When your under throttle heavy load. Every thing is loaded from engine back. When you depress clutch pedal you unload transmission for a gear change. This effects much more than one imagines. In my fleet experience this loss of motion accelerates wear. Engine crank thrust bearing. Modern engine do handle this better. But normally can look at a engine thrust bearing and tell if a driver uses the clutch. Hammers out pilot bearings in flywheel with the movement underload. The shifting underload leads to extended input shaft wear, deep teeth wear patterns on trans input shaft. Which later in life shows up as a clutch engagement issue. A grabby clutch. Now for one that I have zero in print proof but real world witness, I suspect, I see damper springs hammered out of clutch plates. They are experiencing a shock load during gear change. Which end up stuck between plates causing poor engagement. Or just laying in the bottom of flywheel housing.

All cause by a quick change of motion by not properly loading and unloading power to transmission.


On the output side of trans, you have the same issue, it shock load to the complete drivetrains accelerating wear. Could show up in ujoints, differentials.

Everyone is welcome to drive how they want when they own the equipment. But I'll say this, you should know how to double clutch, you will need to someday. For the guys running big power and haul heavy, this multiples x10.

Again. Drive how you want, repair what you choose. The clutch is one of the cheapest parts in a truck. Properly used can save you troubles. Not used properly can be expensive. If everyone is the best gear jammers in the world. We would not have automatics or automatic restrictions on cdl. They are more expensive and not as efficient as a properly shifted manual. But fleets are seeing them as cheaper than improperly shifted manuals.

I typed this before coffee. So don't murder me for any screw ups.

 

Here is a few great videos for guys who wanna learn how they actually function. Very informative.

 

I may not have been very clear. My fault. I agree. But so far there is no automatic or automated trans mission that will out preform a properly shifted manual transmission. The autos do outperform a improperly shifted manual transmission. Which is all driver input and fleets like to control driver input.

 

ATM-s while I'm not very experienced with. The Ultra shifts do use the clutch for shifting and in my lack of proper knowledge on them. They incorporate input and output speed sensors to calculate shifts and uses the clutch.

 

Wore, I have no axe to grind with you or anyone. I was asked for my opinion. I'm providing it. I find you very knowledgeable and informative. One of the best on here.

I'm not seeing your proof. Other than your experience like myself. Am I reading this correct that you claim your loading a crankshaft by disengaging the clutch at a stoplight? A push type clutch will. A pull type clutch would release load from crank shaft. Shifting without clutch hammers the crank back and forth. Again, maybe I'm miss understanding your point. For that I apologize, and yes I do struggle putting thought to print. This is my opinion and experience. I enjoy and appreciate anyone addition. Doent mean I'll agree. But it's welcome.