Gearbox Whine

[AndrewIC]

Well in my case the High Deflection plate has totally eliminated the gearbox chatter, I just need to get to the bottom of this whining and I've cracked it!

 

Is the PRM box new? When my second Hurth HBW100/ZF10M expired, I changed to a PRM120 on my Beta 1305, and replaced the drive plate (the old one had a cracked element) with a standard R&D one. The chatter and rattling from the box at low speeds and idle was dreadful. After a three-way discussion with Beta, R&D and Newage, the recommendations were to increase the idle speed a little, and change the plate to a high deflection one, which I did. The rattling racket went away and was replaced by whine from the box. Advice from Newage was that it should go away after the gears had bedded in, and to give it a couple of hundred hours running time. I did, and it did. Not got the references for the two plates handy, sorry.

[pevil]

 

Is the PRM box new? When my second Hurth HBW100/ZF10M expired, I changed to a PRM120 on my Beta 1305, and replaced the drive plate (the old one had a cracked element) with a standard R&D one. The chatter and rattling from the box at low speeds and idle was dreadful. After a three-way discussion with Beta, R&D and Newage, the recommendations were to increase the idle speed a little, and change the plate to a high deflection one, which I did. The rattling racket went away and was replaced by whine from the box. Advice from Newage was that it should go away after the gears had bedded in, and to give it a couple of hundred hours running time. I did, and it did. Not got the references for the two plates handy, sorry.

 

That's interesting almost the same scenario except my gearbox has done 3600 hours so gears should be bedded in lol, I do wonder though if the old plate wasn't doing it's job i.e. allowing the gears to rattle a little even at speed and now with the high deflection plate the gears are in constant mesh, hence the whine, a long shot but having changed the oil back to 15-40 I think I'll run it a while and see, you never know. Thanks.

[AndrewIC]

Just looked it up. With the old Hurth I had an "AC" element drive plate, fitted a standard "B" type initially with the PRM, then changed it to an "AN" high deflection type (successor to the AC type).

 

This is what what Newage had to say:

 

"Gear whine is basically a tooth meshing error produced at harmonics at the tooth passing frequency. This causes vibration forces during torque transfer throughout the speed range. Gear whine can be attributed to one or a number of certain conditions. This can be caused by gear pitching errors, non-ideal tooth shape, tooth deflection & deformation or the peak frequency band of the vibration force coincides with the resonance frequency of the system.

 

Gear whine is common with many transmissions as helical gears very often whine until they are ‘bedded in’ together & reduce aspherities of both mating gears. I would give the transmission 200hours of varied use before assuming the noise is a problem as previously mentioned when gears are manufactures the tolerances for each gear are carefully controlled to produce the optimal tooth contact. However these tolerances can add up to produce a pair that don’t have optimal tooth contact until they are ‘bedded in’.

 

If the peak frequency band coincides with the resonance frequency a change of drive plate may be able to dampen this condition & therefore maybe necessary to have a very soft drive connection, which must be sufficiently strong to transmit the full torque. The 'R&D Damper' meets these requirements and consists of a moulded element in a new type polyurethane which is fail safe and in the unlikely event of a flexible element failing, the drive is maintained.

 

R&D can offer three styles of Damper Drive Plate. The loop type is suitable for most applications. in some cases the 3 stage stiffness of the Hammer Head or the High Deflection Type is more suitable on torsionally active applications.”"