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Step 1: Diagnose the failure. What part of the tractor is broken? A differential?, Transfer Case?, Axle
shaft?, Drive shaft? This is not a very difficult step if you have a good understanding of the 4WD drive system on a chinese
tractor. You know you have a failure when only one wheel spins in 4WD drive. In 4WD, on these tractors it is not possible
to spin just one wheel, and if it's only both front or rear wheels that are spinning, they have to spin in opposite directions.
When in 4WD, there is a sliding gear that connects the front driveshaft, through the transfer gearbox to the mainline
transmission. On the side of the creeper box is a lever that slides a gear that connects the upper gear of the transfer
case to the drive line that runs through the creeper box.
Below is a diagnostic video that will give you a high level overview of the Jinma 224 drive line. At the end of the video,
it shows the repaired joint that is covered in more detail further down on the page.
| Click On Picture |
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| For Diagnostic Video |
Once you've diagnosed the failure, then it's time to start taking things apart. In my case, the fault was somewhere between
the transfer case and the front differential. A little research on the two primary tractor forums (CTOA and TractorByNet) shows
that the front drive shaft is the most common failure in the 4WD system.
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| Rear Shroud |
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| Rubber Sleeve |
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| Front Shroud |
Step 2: Disassemble the shroud assembly that covers the front drive shaft. Loosen the rubber gasket
and collapse the two halves of the telescoping tube to reveal both ends of the drive shaft. The diagnosis video above already
has the shrouds collapsed to show what was going on.
Step 3: Peel back the front rubber boot and inspect the joint. In my case, the circlip had slipped back
and the balls that lock the shaft into the receiver cup are missing.
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| Under Front Shroud |
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| Under Rubber Boot |
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| Socket Close Up |
Step 4: Once that ball socket was found to be missing the ball bearings, the repair steps are to
pull back the washer and circlip, align the shafts, insert new ball bearings, and reseat the circlip. To reset the circlip,
it will be necessary to pull the shaft back against the spring while seating the circlip in the groove in the driveshaft.
You may need to clean out the circlip groove with a small file so that the clip can be properly seated.
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| Circlip Dislodged |
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| Align Shaft |
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| Insert Balls |
All of the pictures only show one side of the shaft, the 6 ball bearings are inserted 1 per spline
cavity around the circumference of the shaft.
The picture below shows the reassembled joint. After the joint is assembled, replace the rubber boot, the shrouds, and
the rubber sleeve. Repair complete.
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| Reassembled Joint |
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