Spline failure on hydraulic winch
Spline failure on hydraulic winch
(OP)
I'm trying to determine what went wrong with a custom hydraulic winch we had in service.
The winch drum is connected to the frame by an 80x74 DIN 5482, 18NiCrMo5 annealed, case hardened shaft on the dead end, supported by a spherical roller bearing. There is an internally splined bushing pressed into the bearing to accept the splined shaft. Shaft and bushing are held from linear movement by external snap rings on each and a cover plate on the end of the bearing hub. The driven end is supported by the output shaft of a right angle gearbox, also 80x74 DIN 5482. The drum has an internally splined wheel hub (39NiCrMo3/42CrMo4,tempered) welded into each end to accept the splined shafts.
The winch was in service for about 5 years with about 500 hours of run time. It's rated for 12,000 lbs but we measured 18,000 lbs of line pull, so we know it's operating beyond design. However, it still seems like the drum should've been supported some other way than on the two splined shafts. The shaft on the driven end is not lubricated, and the internal splines stripped out of the wheel hub. The shaft on the dead end is greased, presumably only for the bearing. The splines in the floating end of the drum are badly worn, and it looks like there was significant drum wobble before the driven splines stripped.
There's a link to pictures of both sides of the drum and shafts. Any insight you guys can give is greatly appreciated.
winch photos
The winch drum is connected to the frame by an 80x74 DIN 5482, 18NiCrMo5 annealed, case hardened shaft on the dead end, supported by a spherical roller bearing. There is an internally splined bushing pressed into the bearing to accept the splined shaft. Shaft and bushing are held from linear movement by external snap rings on each and a cover plate on the end of the bearing hub. The driven end is supported by the output shaft of a right angle gearbox, also 80x74 DIN 5482. The drum has an internally splined wheel hub (39NiCrMo3/42CrMo4,tempered) welded into each end to accept the splined shafts.
The winch was in service for about 5 years with about 500 hours of run time. It's rated for 12,000 lbs but we measured 18,000 lbs of line pull, so we know it's operating beyond design. However, it still seems like the drum should've been supported some other way than on the two splined shafts. The shaft on the driven end is not lubricated, and the internal splines stripped out of the wheel hub. The shaft on the dead end is greased, presumably only for the bearing. The splines in the floating end of the drum are badly worn, and it looks like there was significant drum wobble before the driven splines stripped.
There's a link to pictures of both sides of the drum and shafts. Any insight you guys can give is greatly appreciated.
winch photos





RE: Spline failure on hydraulic winch
I've never seen a winch drum supported by a pair of splined shafts-alone.
Usually the drum is directly mounted on bearings of some kind and does not rely on the driving shaft for support.
The photos show splines that have undergone high radial loads which has eventually led to a gross misalignment situation. Continued operation under these conditions has resulted in tip/root contact along with non-uniform wear along the teeth flanks. The male spline on the 'dead side' displays a classic 'dog bone' or 'barrel' shape usually associated with misalignment.
Looks to me like a major re-design needs to be undertaken as this problem will continue to occur.
Great photos by the way.
RE: Spline failure on hydraulic winch
Gearcutter, I gave you a star for your post. I really appreciate all the information you gave me.
RE: Spline failure on hydraulic winch
https://www.youtube.com/watch?v=ifBABVClpZY
RE: Spline failure on hydraulic winch
RE: Spline failure on hydraulic winch
If not, then I'd experiment with putting some oil in the drum and setting up some felt to wick the oil to the splines. You can supply a lot more oil that way than a little bit of grease can supply without also introducing the build-up of thickener that occurs as the oil in the grease is depleted.
RE: Spline failure on hydraulic winch
If so; then you need to engage the services of a qualified mechanical engineer with the necessary experience............as a priority!
They will properly evaluate the situation and then advise you accordingly.
RE: Spline failure on hydraulic winch
Many thanks to all for the replies.
RE: Spline failure on hydraulic winch
Then, with a line pull of 18k when 12k lbs was the rated capac., how did the wire rope look like? If the rope was rated 12k lbs as well, I would not consider this mechanism noncritical to possible injury... even if the winch was safe.
Pls. be sure to redesign the complete appliance to the required rating.
Regards
RSVP
RE: Spline failure on hydraulic winch
RE: Spline failure on hydraulic winch
you pls. be careful when re-evaluating, checking what is and what you want...
.. as design standard:
Just take e.g. FEM II for a general base & the current state of things, with 500 h you are in utilz. class T2 and if the 18k is the usual load spectrum class is L4, which runs together into a mech. class M4. Minimum practical safety factor to be 4.
Regards
RSVP
RE: Spline failure on hydraulic winch