nylon lock on nut vs loss of preload when torquing
nylon lock on nut vs loss of preload when torquing
(OP)
"ADMINISTRATION KILLS ENGINEERING"
I am rigidly mounting a diesel engine with a through hole/slot that is connected to a rigid solid skid base.I am using 1 inch grade 8, coarse tread, zink plated shoulder bolts,washers at both ends and nuts have a nylon lock to help prevent loosening because of vibrations.
I am limited to a maximum clamp force of approx 80KN
Now the basic equation for relationship between torque and preload is
Fc=5T/D
Where
T = 80 000 N * 0.0254 m /5 = 406 N m
I would like to know:
1. should I account for losses by friction in the nylon ?and if so by how much ?
2. Will the pre-load obtained with this torque be appropriate for this joint (considering the harware used)?
Now i intend to torque dry at the head of the bolt and would like to know if anyone has comments or observations.
thanks to all
I am rigidly mounting a diesel engine with a through hole/slot that is connected to a rigid solid skid base.I am using 1 inch grade 8, coarse tread, zink plated shoulder bolts,washers at both ends and nuts have a nylon lock to help prevent loosening because of vibrations.
I am limited to a maximum clamp force of approx 80KN
Now the basic equation for relationship between torque and preload is
Fc=5T/D
Where
T = 80 000 N * 0.0254 m /5 = 406 N m
I would like to know:
1. should I account for losses by friction in the nylon ?and if so by how much ?
2. Will the pre-load obtained with this torque be appropriate for this joint (considering the harware used)?
Now i intend to torque dry at the head of the bolt and would like to know if anyone has comments or observations.
thanks to all





RE: nylon lock on nut vs loss of preload when torquing
2) The preload does not seem appropriate for this application. Typically, the minimum bolt preload is ~ 50% time the proof force. Your fastener size and strength mean 50% of proof is much higher than 80 kN. Therefore you should choose a smaller fastener or a weaker material.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: nylon lock on nut vs loss of preload when torquing