NYSDOT PTSB SAFETY ADVISORY
Re: LOOSE LUG NUTS ON TRANSIT BUSES
DATE: October 7, 2012
ISSUE: Results and recommendations from survey
It is advised that all PTSB bus properties review the recommendations attached in this advisory and implement them if not currently in place.
As a result of two loose wheel incidents in 2011 (attachment 1) and a PTSB survey conducted in 2012 of all PTSB jurisdictional properties (attachment 2), the PTSB staff recommends the following actions to ensure proper securement of all bus wheels (this is in addition to generally accepted maintenance practices for wheel securement and is specific to loose lug nuts):
MAINTENANCE
- The most common cause of loose lug nuts is an under torque or over torque condition. Therefore, it is recommended that proper attention be paid to ensure that correct torque values are maintained in accordance with the requirements stipulated by the manufacturer of the bus. Develop and implement a re-torque program which is to be utilized whenever wheels are removed. Data should be collected and documented in file as to torque rates, dates, and bus mileage. Re-torque should occur after 50-100 miles of use, or at mile intervals as recommended by the manufacturer. Quality torque rating equipment must be used and data filed with maintenance records. Torque should be applied by a correctly sized, properly calibrated impact gun, torque wrench, or other torque rating equipment. Do not check torque values when wheels are excessively hot (from recent use), as false values can be indicated. Note: a 1” impact gun (impact wrench), commonly used in garages can easily over torque to a 500 ft/pound rating. AN IMPACT WRENCH, IF NOT PROPERLY CALIBRATED, SHOULD NOT BE USED TO ESTABLISH FINAL TORQUE VALUES.
- Do NOT use an anti-seize compound on studs or vertical mounting surfaces.
- During PMI’s and after wheel removal, inspect for crushing of slinger material under inner nuts and washers which is an indication of high bolt tension from an over-torque condition.
- During wheel changes, look for stud fatigue fractures which are indications of long time loose wheel studs.
- All identified failures of any type should be documented in the maintenance file and reviewed for a potential fleet trend.
- Some systems have had success using loose wheel lug indicators to assist bus operators identify loose lugs during their pre-trip or post-trip inspections.
- Report wheel off failures (required by regulation) or chronic part failures to your local PTSB Investigator or NYSDOT MVI for follow up action and advice.
When I was mo young I worked like I was 23 when I was 58.
Those daze are gone too..................
I just wanted to post that those more young than Me should see it all as a Mans job.
I wish you all the best
......................And wasted wheels make great fire pits.
I R or was 91B2P and a machinist mechanic engineer worker bee.