How to weigh axles on a scale that only gives you gross weight?

I was taught to pull up until the next axle set is close to the scale. Then take a reading. Before pulling the next axle set on.

Weight will be more accurate.

 

In any type of description of plumbing, one would hope that 'T' would readily be understood as 'tee', which is a word, both a noun and a verb.

 

Air suspension gauge, probably not in a lot of cheap, low spec company trucks.
It measures air pressure in the air bags. And once you know the truck you will know that for example 59psi equals 34000lbs on drives. Anything that has an air bag can be measured. So if you have air ride steer, air ride drives and air ride trailer you can measure psi in all of them. You don't really need it on steer axle as that doesn't typically change much.
Most would just use air suspension pressure to get a good approximation of weight. If gauge shows really light don't worry about hitting a scale. If it shows heavy them maybe go hit the cat scale.

Like I said I've loaded literally thousands of loads of grain using just air pressure gauge and could get pretty darn close.

 

They can either be spec’d from the factory or installed later. Most people that run their own trucks have them for convenience. Most fleets don’t run them because they’d rather you waste half your day driving back and forth to a Cat scale.

 

I drove a Kenworth T-660 that had the air gauge in the dash cluster. I don’t remember the exact number anymore, but it told me if I was going to be over on the drives. If I was fairly sure that the BOL weight was accurate, I wouldn’t bother with CAT scales.