GE's 2 & 3 AXLE TRUCKS EXPLAINED
AAR and FB-2 TRUCKS(2 AXLE)
AAR Type "B"-Two high mount brake cylinders.
Floating Bolster used on many "B" road units. Wheelbase 9'-00".
FB-2 One high brake cylinder, one shock.
There is a drawing and article by Jerry T Moyers on the FB-2 trucks in the April 1974 issue of Railroad Model Craftsman. According to the article this truck was introduced on production models in 1973 and replaced the AAR type "B". A couple earlier demonstrators units used these as well as the Auto-Train U36b's in July 1972.
GENERAL ELECTRIC 3 AXLE TRUCKS
The first 3 axle trucks were used on the U25c were a modified deep frame similar to the Alco tri-mounts. The Phase l U28c's also used this truck. The FB-3 trucks were introduced in 1966, under the Phase ll U28c's. The FB-3 Adirondack version and the General Steel Casting's version have been used on all 3 axle units until the introduction of the Dofasco HI-Ad truck in 1993 on the 9-44CW's for the C&NW. All FB-3's have a wheelbase of 13'-07".FB-3 ADIRONDACK VERSIONS
Here are four versions of the Adirondack. A good spotting feature is the casting hole, it is near the end wheels and the bottom of frame is parallel with the tracks and only rises over the center wheel.
AD2LES-Two low brake cylinders, shocks above end wheels.
AD2LCS-Two low brake cylinders, single shock over center wheel.
AD2H-Two high brake cylinders, no shocks.
AD3HCS-Three high brake cylinders, single shock over center wheel.
FB-3 GENERAL STEEL CASTINGS VERSIONS
Here are four versions of the GSC Trucks. A good spotting feature, the casting holes are centered between the wheels and the bottom of frame rises over all three wheels.
GSC2LES-Two Low brake cylinders, shocks above end wheels.
GSC2HCS-Two high brake cylinders, single shock over center wheel.
GSC2LCS-Two low brake cylinders, single shock over center wheel.
GSC3H-Three high brake cylinders, no shocks.
When modeling any GE engine it is best to refer to a picture as these trucks were used interchangeably. In fact some engines had both types due to field changes.
This does not cover the later Dofasco Hi-AD types. Maybe later...Sam...