Hi Wuhuan,
I am having transmission problems with 2 identical Heli Models #CPYD35, Serial #23035C1231 and 23035C1232. Both have GM motors and Heli Y-3 Transmissions.
We have sold 2 of these to our customer through a local dealer. It is a very rough enviroment and both units had the transmission output shafts snap at the base of the spline at aprox 3500 hours. Most likely from the same driver using transmission to stop 10kLBs within 3 months of each other. We replaced the shafts and decided to put clutch disks, plates and seals in also. We did one transmission at a time and have pressures in the right ports but have only reverse in forward, reverse in neutral and reverse in reverse. On the bench clutch packs are free, forward and reverse close respectively to the ports under light air pressure. We rebuild alot of transmissions here and have never experienced this problem before. We thought the 3 clutch pack plastic seal rings broke during install but after dismantling found them in new condition. Never saw plastic seal rings before this transmission, they are usually steel interlocking rings. We then did the second unit because we needed one of them to work right away and ended up with the dupicate scenario. We have tested the pressures and everything seems to be right. We are wondering if the 3 plastic seal rings on the clutch drum shaft might be at fault and may have been upgraded to metal or what else we could be missing. Both units have identical problem. Whatever we did or didn't do we evidently did the sameway wrong. Please help us if you can. My email is [email address removed]. Thank you in advance for your consideration.
Larry Beals, Forklift Mobile Inc.