Jinma Shifting Procedure

Carld · Jun 28, 2006

The Jinma transmissions are not made to shift on the go. Nor is any non synchro transmission. When you say square cut gear it normally means the the teeth are cut parallel to the axis of the gear shaft. Helical is cut on an angle to the axis. Both straight and helical usually have the edge of the teeth beveled. To shift on the go you must match the speed of the drive gear with the speed of the driven gear. To do that you have to double clutch with very little throttle to upshift. To downshift you must use a lot of throttle. It requires a lot of practice to do it right and you may have to replace gears also. Having rebuilt transmissions and replaced clutches a lot I would much rather replace the clutch than rebuild the transmission. Every time you shift on the go and hear the crunch you are eating the edges off the gears. You will get metal in the oil and besides eating up the gears you will damage the bearing with the metal shavings. But, it's your tractor, do as you wish.

ejtaylor822 · Jun 28, 2006

Soundguy said:
.....Perhaps enjoy a cold beverage as well.

I'll have one waiting for you if you are ever up this way.

Mike_Lipke · Jun 29, 2006

"shift on the go. Nor is any non synchro transmission"

Not true. I've driven hundreds of thousands of miles on Diesel semi trucks, non of which had sychro mesh transmissions.
Only as I was learning did I ever crunch gears. It is a skill that must be learned on trucks. Tractors? Well, either you learn it, or don't do it.
I can tell you that you are not going to get 80,000 lbs started from a stop in a higher gear. Period.
Some trucks have 13 or 16 gears, all double clutched, or, if you are really good, no clutch.

Soundguy · Jun 29, 2006

Tractor trannies and truck trannies are 2 worlds apart. Tractor trannies are designed to move start the tractor in any gear.

On big trucks.. 1-3 is the start.. You wouldn't start in 10.. etc.

Also in the mix is the method of switching ranges. Many tractors have a seperate gear shift for ranges.. some have rabit/turtle toggle switches for electric solenoid switch over.. still others are hyd or some combo of electric over hyd. You've got the ford Dual power system.. other brands have the TA system.. etc Many trucks have the simple push pull switch for high/low on the gearshift itself...

Lets keep it apples to apples...

Soundguy

ZionHill · Jun 29, 2006

I tried it last night.

On a flat section of driveway starting off in 2nd I was able to shift to 3rd quite easily.

However from 1st to 2nd was not that smooth because the inertial binding of the gears is tight down that low.

Downshifting even with double-clutching was not possible. By the time you've gotten the tranny speed down low enough you're almost coasted to a stop.

Starting off in 3rd in high range on my tractor takes a lot of slippage so it looks like for me up-shifting is the way to go.

It was a fun experiment that actually yielded something.

MrFixit · Jun 29, 2006

I sure would not buy a used, Non synchro tranny tractor from a guy who shifts while moving.

crazymike · Jun 29, 2006

also, if you arn't comfortable with double clutching, remember you are driving a tractor.

You have tonnes of power and it's near impossible to stall in any gear with no load. Just keep your revs high enough not to stall and use the engine to break.

The only time I find myself shifting down is on the road. And unless you reach a steep grade you don't usually need to downshift.

If you are slowing down for a corner, etc... you can usually stay in a higher gear.

Soundguy · Jun 29, 2006

I've found just throttling down in high gear gives you plenty of breaking for corners.. etc.

Soundguy

HomeBrew2 · Jun 29, 2006

Just curious. If I read correctly, it seems there's been reference to actually grinding the GEARS when shifting a tractor transmission (I'm not referring to the range selector). If so, are tractor transmissions NOT constant mesh like automotive transmissions? That is, when you hear grinding in a standard auto/truck transmission it's the dog clutches grinding, not the gears, as the gears are all meshed all the time.