If one was looking to purchase trailer axles, there are a few places on can look. One can go down to a local trailer dealer and see what they have for a selection. If one is looking for a cheaper alternative, a local scrap yard may have trailer axles.
If you have a sliding fifth wheel, you can transfer weight from the drive axles to the steer axle by sliding it forward, or you can transfer weight from the steer axle to the drive axles by sliding it back. If you have sliding tandems on your trailer, you can transfer weight from the drive axles to the trailer axles by sliding the trailer axles forward, or you can transfer weight from the trailer axles to the drive axles by sliding the tandem axles back. If you don't have these options, you have to readjust your load.
Normally there will be 5 or 6 axles. 1 steering axle 2drive axles and either 2 or 3 trailer axles.(Some states do allow more trailer axles.)
Steel.
It depends on what the freight is and what the trailer is. If it's vehicles, you typically drive them on and off. If you have a van trailer with sliding tandems, you would ideally want the weight distributed fairly evenly between your drive and trailer axles. If you had a trailer with spread axles, you would want more weight towards the trailer axles, since you're allowed 40,000 lbs. on a set of 10 ft. spread axles, as opposed to 34,000 lbs. on your drive axles.
What's typically referred to as an 18 wheeler has five axles - steer axle, two drive axles, two trailer axles. Tractor-trailer combinations can have less or more,, depending on the application.
A truck with three axles,(1 steering and 2 drive axles) is called a tandem.A trailer with 3 axles is called a tridem or a triaxle depending on the spacing between the axles.Number of axles is not specific to any one manufacture.
Yes, but there could be a toll charge associated with that route. Tolls are based upon the number of axles and total weight. A car towing a trailer would have 3 axles at the minimum, 4 if the trailer has dual axles.
The "tractor" is the vehicle which actually powers the combination. A semi-trailer is any trailer in which the weight of the trailer (and the payload) is shared between the trailer's axles and the axles of either a dolly or the towing unit (in contrast, a full trailer supports all of its own weight).
The question's a bit vague. If you're referring to distributing weight once you're loaded, it depends on what your trailer has for axles. If you have fixed tandems or a fixed spread axle, you would have to move the load itself. If you have sliding tandems, you can move them forward to shift weight from the drive axles to the trailer axles, or you can move them back to shift weight from the trailer axles to the drive axles. If you have a sliding fifth wheel, you can move that forward to shift weight from the drive axles to the steer axle, or you can move it back to shift weight from the steer axle to the drive axles.
As evenly as possible between the drive and trailer axles.
All axles have brakes on them.
A trailer with 10' California spread can have 40,000 on the trailer axles without requiring a permit.