Jinma Shifting Procedure

[HomeBrew2]

Most gear tractor trannies are not Synchromesh...

Soundguy

Well, yeh, I think that's pretty well known and is accepted by all on this thread. Synchros are an added feature to the dog clutches of a constant (gear) mesh transmission that equalizes the the speed of the input and output of the transmission so the dogs can engage without the operator having to match those speeds manually (skill) or by double clutching (not much skill).
My reference and question was about the comments about "grinding" the GEARS in a tractor transmission, which is impossible in an automotive transmission because all gears are always meshed. My guess is that tractors have a similar transmission and the "grinding" is really the dogs grinding just like in a car/truck. My guess is that nobody has made a non-constant mesh transmission for 100+ years ... ?

 

[Soundguy]

Looking at my old ford tranny diagrams.. i just see bearings, bushings, a couple thrust washers, shifter rails.. counter shaft, some seals and gaskets, the gears, and splined connectors and splined couplers. Mind you.. these are all sliding gear trannies.. in various 4 spd and 5 spd setups. Don't seen any dogs... or any thing like that... ( i'm not a transmission guy.. but.. looking a the exploded diagram... .. every part is identified.. )

Am I missing something? One of my tractors.. the 2002 NH mentions it has a constant mesh transmission. None of the other tranny sections mention that.. though.. like I said.. I'm not a tranny guy. What would these 'dogs' be called in a tranny diagram... And in any case.. if they are grinding.. that's still metal in the oil.. right?

Soundguy

 

[HomeBrew2]

Looking at my old ford tranny diagrams.. i just see bearings, bushings, a couple thrust washers, shifter rails.. counter shaft, some seals and gaskets, the gears, and splined connectors and splined couplers. Mind you.. these are all sliding gear trannies.. in various 4 spd and 5 spd setups. Don't seen any dogs... or any thing like that... ( i'm not a transmission guy.. but.. looking a the exploded diagram... .. every part is identified.. )

Am I missing something? One of my tractors.. the 2002 NH mentions it has a constant mesh transmission. None of the other tranny sections mention that.. though.. like I said.. I'm not a tranny guy. What would these 'dogs' be called in a tranny diagram... And in any case.. if they are grinding.. that's still metal in the oil.. right?

Soundguy

Soundguy,
I am far from being a "transmission guy" but I have had to get knowledgable about such things. Respectfully, you may be missing something but I don't think anybody cares. And I am starting to care less by the minute. I was just responding to the goofy notion that jamming gears was actually harming the actual GEARS themselves. That's impossible. Tearing the dog clutches apart? Yep, that's a real possibility and, YEP, that means chips in the pan, and that is bad!
I know that intelectually it may not be a great resource, but check out HowStuffWorks. Search for "transmission". they have a great interactive (manual) transmission tutorial.
Cheers! Sorry i even brought it up.

 

[greg_g]

...I was just responding to the silly notion that jamming gears was actually harming the gears themselves. That's impossible...
Sorry i even brought it up.

I am too.

But since you persist in this notion, how about pointing out to us the dog clutches in the attached Jinma tractor drive train diagrams. Then perhaps you'd enlighten us as to how no damage could possibly occur to some of those slab-sided straight-cut sliding-rail gear teeth if/when are forced to engage under revolution and pressure .

I respectfully submit that as this type tractor drive train ages it actually becomes easier to shift gears - on the fly or normally - because of the fact that doing so since new has rounded the edges of the gear faces - thereby making it easier to mesh under rotation than when they were new.

//greg//

 

[HomeBrew2]

Thanks for helping to straighten me out Greg! Though I didn't get much more from your diagram than the fact that there definately are no dog clutches, my neighbor happened to have an old 8N manual which had a really nice cutaway shaded drawing that showed clearly how the straight cut gears have to slide into each other. So, I very happily learned something: a tractor transmission is nothing like a highway transmission. And, I can sure see how experimenting with trying to change gears while moving could do real damage. I noticed the 8N manual showed pretty big chamfers on the gear corners to help getting it into gear. Kindof amazing to me that a guy could ever change gears while moving ... almost seems like it would be a trick while stopped.
Thanks for the help, cheers!

 

[bluechip]

The JInma 200 and 300 series and the KAMA TS series tractors have sliding gear non synchro tranmissions. When you shift these you are sliding gear sets into and out of mesh, when you hear gringind, it is the same teeth that must also drive the tractor. I do not recommend shifting on the move on this type. the KAMA KM454 and KM554 have constant mesh, non synchro transmissions The actual driving and driven gear sets are all in mesh (not reverse) and you slide dog clutchs that engage a pair of gears or another on the shafts. These can be shifted. If you hear "gears ginding" it is the teeth on the dog type clutches and not the driving teeth. of course damage to these teeth will also render the transmission inoperable as the gears will still turn but not the shaft. as has been said, synchro rings were added to help people shift at the wrong times and the wrong rpms and make it much easier to downshift. I am not aware of any common Chinese tractor with sychro but I have not checked them all.

 

[HomeBrew2]

Bluechip,
WOW!!!!!! I can sure see now why you have such a good rep among Chinese tractor owners on this board! VERY GOOD INFO! I may be the only guy that learned something from this thread, and I sure enjoyed the education. Thanks to you and Greg and my neighbor (who had an old 8N manual) !

Cheers!

 

[Soundguy]

I had an inkling there were no 'dogs' as you calle dthem in our tractor trannies. As I said.. I'm not tranny person.. but I've helped repair a few tractor trannies.. and it is just pretty much sliding gears.. at least for the kind we are talking about... And thus.. that's why you can get chipped gear teeth.. etc.

Soundguy

Thanks for helping to straighten me out Greg! Though I didn't get much more from your diagram than the fact that there definately are no dog clutches, my neighbor happened to have an old 8N manual which had a really nice cutaway shaded drawing that showed clearly how the straight cut gears have to slide into each other. So, I very happily learned something: a tractor transmission is nothing like a highway transmission. And, I can sure see how experimenting with trying to change gears while moving could do real damage. I noticed the 8N manual showed pretty big chamfers on the gear corners to help getting it into gear. Kindof amazing to me that a guy could ever change gears while moving ... almost seems like it would be a trick while stopped.
Thanks for the help, cheers!

 

[Carld]

Mike Lipke, semi trucks transmissions have constant mesh gears with what is called slip clutch gears to engage each gear set. Most of them have a central input/output shaft with floating gears and sliding gears on it that engage the center of the floating gear of 1 thru 5 with countershafts on each side to balance gear load and transfer the motion to the output shaft. Reverse uses a sliding gear. Yes, you have to double clutch to shift smoothly but the gear teeth stay in constant mesh and the clutch gear slides in and out of the center of the gear you select. There can be a two speed box on the rear of the trany as well as an overdrive gear set. I was a diesel mechanic for about 17 years and had a lot of them apart. The old Model A Ford was non syncro and used sliding gears like our tractors. You had to learn to double clutch them also BUT, they had a higher road speed than our tractors. It was not to bad going from 2nd to 3rd or 3rd to 2nd but to go to from 2nd to first on the roll was tricky and many a trany was damaged. Our tractors have sliding gears and because of the rotational speed of the gears compaired to the ground speed It is tricky to shift on the go. You can do it but everytime you miss a little and it grinds or goes CHUNK and jerks you are damaging the teeth and you WILL be rebuilding the trany. I can start my 254 in 2nd on a 20deg hill here with little trouble. Starting in 3rd can only be done on the flat or down hill areas. You have to learn how to engage the clutch and use the throttle and I slip the clutch very little. I have shifted on the go to see if I could do it but one slip and it could be a big repair job. To me this is a discussion so how you treat your tractor is a moot point. The main thing is to have fun and get work out of the tractor and enjoy the discussions.