140,000 lb. GCWR

If your customer is truly grossing 140,000, without a pusher, ask if they would accept rear axles rated at 40,000 lbs. This may sound counter-intuitive, but it makes perfect sense.

There are some sales tools which cap models, or major components, at a maximum GCW below the actual customer value. If this is the case, make certain you narrate the actual GCWR so that engineering runs all their programs with the real values. Also run your gearing using the real values. If the actual value is over 160K, you should consider the 46K rear ends.

Let’s use the Dana Application sheet as an example. A D40-172, is good for line haul up to 160K, Operation 2 (8%) grade up to 4.10 gearing. Many 40K rear suspensions are good for 180K lbs. 

If you are using a lift axle, the creep rating for the rear suspension drops, but most 140,000 lb. GCWR chassis only need a 13.5K lift axle, or no lift at all.  So, this should not be a deterrent.

There are other advantages to the lower capacity axle. Most of the time Engineering won’t require an insert, where they can be required with 46,000 lb. rear ends.  Therefore, you won’t need the more expensive, axles, suspension or insert, if 140,000 lbs. truly defines the operation.

I review a number of 140K heavy haul chassis, and they have either a 46,000 lb. rear axle, or even 52,000 lb. First of all, heavy haul really is over 140,000 lbs. GCWR.  Perhaps you have the wrong vocational data, or your customer is pulling heavier. A 52K rear and is good to 240K, that’s a huge delta from the spec data. Understand what the customer is really telling you.