Jinma 284 new owner have some questions

[RonMar]

I have encountered a different problem, sometimes when I try to start the tractor, the starter spinns but it is not engaging the flywheel, this sounds a bit like the clutch in the starter is slipping or has failed. Any opinions?

Thanks .. J

There is no clutch in the starter... The solenoid(smaller tube attached to the starter) is an electromagnet. When power from the key is applied, it does two things. It closes a high current contactor between the two large terminals on the end. In the other end the solenoid pulls a lever which operates a slider gear on the motor shaft. The slider gear slides to the rear and engages the teeth on the ring gear to rotate the crankshaft.

What may be happening is the "yak fat" these things came lubed with from the factory has set around long enough that it has hardened. Disconnect all the cables from the starter. Start with the battery negative terminal to keep from shorting anything out. Remove the starter and take off the solenoid. clean out all the old grease around solenoid, lever and sliding gear, and re-lube with new modern moly grease... that will probably fix the problem.

 

[Jasper661]

RonMar

The tractor was sitting for three years, before I bought it, I will take it apart and clean and re lube. I had found a post mentioning a clutch on the starter of 200 series Jinma..?

Thanks..J

 

[Jasper661]

After dissasembling my starter this morning I can say for a certitude that there is a clutch. But it seems to be performing it's designated function. During my dissasembly I noticed that the pivot for the arm that transfers the solenoid motion to the starter shaft, is an eccentric. If that has loosened up over time, it would change the engagement between the starter gear and the ring gear. Other than that my starter seems to be functioning correctly.

 

[RonMar]

Can you take a pic of this clutch? Never heard of one in a starter...

 

[Jasper661]

RonMar

I have it all back together and since adjusting the pinion engangment is is starting nicely. All starters have to have some sort of a clutch mecanism, to disengage the starter motor from the ring gear when the engine starts. This device has the same function as a centrifical clutch, it is attached to the starter motor shaft and has the pinion geat attached, it lockes in the direction of starter motor rotation and then "free wheels" when the engine starts.



Here is one from am image file, but they are all just variations on a theme.

 

[Bob Rooks]

RonMar

I have it all back together and since adjusting the pinion engangment is is starting nicely. All starters have to have some sort of a clutch mecanism, to disengage the starter motor from the ring gear when the engine starts. This device has the same function as a centrifical clutch, it is attached to the starter motor shaft and has the pinion geat attached, it lockes in the direction of starter motor rotation and then "free wheels" when the engine starts.

View attachment 378449

Here is one from am image file, but they are all just variations on a theme.

Not a centrifugal clutch at all. It's a Sprag Clutch. Almost all starters have them, whether they are air, hydraulic, or electric.

 

[RonMar]

Yea, OK, I guess technically that is a clutch... Wasn't what I was envisioning wen you were refering to a clutch...

 

[Jasper661]

Actually Ron is closer to the mark, for a device to be a clutch thare needs to be some sort of friction coupling, the devices on starters are solid unidirectional connections. In the strictest sense not clutches at all, accept in common terminology.

 

[Bob Rooks]

Being a native Californian, every time I hear the term "Cali" I want to throw up. "Cali" is a nickname for the town of Calexico.

 

[Bob Rooks]

Actually Ron is closer to the mark, for a device to be a clutch thare needs to be some sort of friction coupling, the devices on starters are solid unidirectional connections. In the strictest sense not clutches at all, accept in common terminology.

They are in every sense of the word a clutch, hence it's name. It's just that your knowledge is limited to the automotive friction disc type. Look at the illustration again and tell me there is no friction involved, it's just steel against steel instead of woven media.