How well do you know Used Dumps? Part 1 w/more to come. Converted tractor or gorgeous dump? Can you tell?
Converted Dump Tractors. There are tens of thousands more tractors (5th wheel) than correctly designed dumps on the used market. In this example, we left the 13.2K steer and moved 10,500 to the pusher. Steer creep is now 16K which the axle can handle, but the steering gear can't. Eventually the springs could fail.
No OEM builds a 20K steer with a single steering gear, so that’s a quick indicator. You’re hoping for twin gears or a single w/assist cylinder. I'm not fond of the assist cylinder, (given the environment it lives in) but it does satisfy the steering need. 20K axles are STD with two steering arms. 18K and smaller only have one.
Say the chassis has a single pusher (lift axle ahead of the drives) with a 243" w.b./54" tandem spread, or a 244” w/52” or a 245” w/51” (both 51”/52” are also possible tractor indicators with a 4' bridge). Federal/state bridge for 23 ft. is 57,500 lbs. Subtract 20K steer, 34K drives leaves 3.5K on the pusher ground load. Now subtract the tare weight of the pusher, say 1.5K, that leaves only a 2,000-lift axle payload. That lightly loaded axle will flat spot tires, so ask if a LQ-5 valve was added, which helps. It can be added aftermarket if the OE doesn't offer, and most don't.
One state requires 10K minimum. Another state doesn’t recognize lift axles along with some provinces and territories. It's important to know what's required, when working with customers outside your AOR (Area of Responsibility)
Some states and/or construction zones allows 22,400/axle. Example: 20K steer, 22K pusher, and 44K on the drives. Total 86K. Now, calculate weight on the steer (Creep/site lift axle raised) 27,188 lbs. so are your steering gears designed for this? Also, check the drive axle and suspension ratings, they both have creep/site ratings as well. Some OTR (Over the Road) chassis suspensions don’t have rating, thus no lift axles are permitted.
Given today’s reduced stopping distance, adding a lift axle on a tractor is not recognized. They are only allowed at the factory where ABS, ATC, ESP/ESC takes this configuration into account. 250 feet max at 60 MPH, is a tractor requirement.
Without a pusher, the GVW (Fed Bridge) on three axles is 53K, a 4.5K difference.
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