BROKEN BOLTS 2

[Prime9.9]

Hi,

Im facing this problem frequently now,my bolts are always breaking at a regular interval . The bolts are unit of torque hub speed reducer. How to identify the reason for this issue and rectify it. Please provide your kind feedback on this issue.

Thanks

 

[Prime9.9]

Thanks a lot gents for your valuable feedback

 

[drawoh]

Prime9.9,

Is it those four bolts that always break, or all the bolts all around?

--
JHG

 

[Prime9.9]

drawoh,

It's random actually but one or two regularly breaks.

Prime9.9.

 

[kingnero]

At that size of the claimed large M24 bolt and nut, the METHOD of torquing is critical: You should be applying the torque (which is needed to get the pre-load required for successful operation) in 3 or four stages towards maximum torque (of 25%, 50% 75% 90% and final torque) by a qualified operator using a calibrated torque wrench in a star or hex pattern around the entire joint. Is this being done properly? Have you inspected the operators ACTUALLY DOING the installation? If they are using an air impact wrench to "just drive them down dry" - then, YES. THE BOLTS WILL FAIL.

Most likely, working based on torque values alone doesn't cut it: torque + turn of nut, hydraulic tensioning or torque-indicating washers are necessary.

---

http://be.linkedin.com/in/fusionpoint

 

[drawoh]

Prime9.9,

Do your bolts break at installation, or do they break while the thing is being used?

Also, is that a wheel? Are you lifting it off the ground when you install the bolts?

--
JHG

 

[WKTaylor]

Any photos of actual fractured bolts... including side views and end-onto-fracture views??

Also.. are these true bolts [with precision shank and short threads]... or are these cap-bolts [mostly threads, little bearing shank]???

Also, in the application shown, I would expect to see 'wheel-nuts and studs'... not plain nuts with washers on studs that 'barely looked long enough' to do the job.

This is strictly a SWAG... Bolts under probably strength and/or are an alloy that does NOT have good fracture toughness at the HT strength... and/or the threads are coarse and are machined-threads as-opposed to cold/warm-rolled fine threads... Ohhh.... there is a likelihood for poor control of the thread root and general profile.

Regards, Wil Taylor

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[rb1957]

d'ya mean the bolts are "cr@p" ?

another day in paradise, or is paradise one day closer ?

 

[Ron]

Based on your photo, you have several different bolts and nuts. Likely different grades.

The Torque-Hub manual for the 11HBX02F series shows these items to be 5/8-18 or M16 studs or bolt, probably depending on the OEM specs.

The manual also gives a tightening sequence and the bolts/nuts are to be tightened to 35-45 ft-lbs and cautions to not overtighten.

 

[rb1957]

odd that OP insists they're M24 ...

another day in paradise, or is paradise one day closer ?

 

[drawoh]

rb1957,

If he is applying the torque for M24s, the broken bolts are explained.

--
JHG

 

[racookpe1978]

M24? Might be the wrench size for a 5/8 (M16), not the bolt dia.