Tom's Technical Section


Home
Page 1 - Wheel and Axle Standards
Page 2 - Car Frames
Page 3 - Track Twist Gauge
Page 4 - How to Build a Coupler Pocket

Wheel and Axle Standards

All Dimensions in Inches

Scale
Standard
Track
Gauge
T
Tire
Width
W
Flange
Width
F
Flange
Height
R
Contour
Radius
B
Back
Gauge
G
Wheel
Gauge
wheel
check
12"
prototype
56.50
5.50
1.156
1.125
.688
53.38
-
54.53
3/4"
scaled
prototype
3.531
.344
.072
.070
.043
3.336
-
3.408
3/4"
BLS
3.5
min
.406
min
.094
max
.094
max
.047
+/-.008
3.281
+.020/-0
3.470
+0/-.020
3.375
ref
1"
scaled
prototype
4.708
.458
.096
.094
.057
4.448
-
4.544
1"
BLS
4.750
min
.505
min
.125
max
.140
max
.062
+/-.010
4.437
+.020/-0
4.690
+0/-.020
4.562
ref
1.5"
scaled
prototype
7.062
.688
.144
.141
.086
6.672
-
6.816
1.5"
BLS
7.250
min
.750
min
.156
max
.187
max
.094
+/-.015
6.870
+.020/-0
7.190
+.020/-0
7.031
ref
1.6"
BLS
7.500
min
.750
min
.156
max
.187
max
.094
+/-.015
7.120
+.020/-0
7.440
+.020/-0
7.281
ref


Tom Bee Standard Wheel Profile


  This drawing represents the wheel profile which I use on all of my wheels.  The 
  dimensions shown are taken from the IBLS standards with the exception of a few.

  1) The small radius at the end of the wheel tread.
       I use a .020" radius to eliminate the sharp corner.

  2) The wheel tread angle.
       I use 3 degrease instead of  2 degrees, 50 minutes.
       This decreases wheel slip on curves and improves centering on straights.
  
  3) The flange radius.  (not the fillet radius)
       My radius is .070" due to the thicker flange.

  4) I have scaled a dimension using a prototype drawing from Union Pacific
     which IBLS does not specify. This dimension (.040") pertains to the
     rail guard contact surface on the backside of the wheel. The ten
     degrees contacts the backside of the wheel .040" below the rail.
     (this dimension is .375" for prototype practice) Most modelers start
     this angle at the wheel tread.  On some wheel profiles there is no ten 
     degrees at all.  I feel the benefits are as follows:

  1)     Makes the ten degree flange thicker.
  2)     Creates a positive surface for guardrails.
  3)     Reduces picking or climbing frog points.
  4)     Improves guiding through crossings.
  5)     Indicates a dimension not specified by IBLS.
  6)     Can be applied to all wheel diameters.
  7)     Can be carried over to other scales using proper dimensions.
  8)     Makes all wheels in the hobby more uniform. Without this dimension
         it leaves that part of the wheel profile vacant which I feel needs
         to be filled.

       Tom