Tanat Valley 3 by Peter Drost
Latest News
- Andrew Campbell RIP - from the Chairman - 18th Sep
- David Hunt 1947 - 2026 - from Adrian Tester - 18th Sep
- New S7 DMU wheels available from the Stores - 17th Sep
- S7 Newsletter 145 (August 2026) is now available for download - 28th Aug
- Dave Hunt - from the Chairman - 24th Aug
- Rob Thompson - from the Chairman - 30th Jul
Working Dimensions and Tolerances
The numbers refer to the table on Track and Wheel Standards and correspond with those on the other pages in this section.
|
ScaleSeven Standard Dimensions |
mm |
in |
||
|
1 |
Track gauge (straight track) |
min |
33.00 |
1.299 |
|
2 |
Gauge widening |
max |
0.45 |
0.018 |
|
3 |
Tyre width (loco) |
min |
3.16 |
0.124 |
|
Tyre width (loco) |
max |
3.26 |
0.128 |
|
|
Tyre width (coach and wagon) |
min |
2.90 |
0.118 |
|
|
Tyre width (coach and wagon) |
max |
3.00 |
0.118 |
|
|
4 |
Back-to-back |
min |
31.20 |
1.228 |
|
max |
31.30 |
1.232 |
||
|
5 |
Effective flange |
0.66 |
0.026 |
|
|
6 |
Back-to-back + one effective flange |
min |
31.86 |
1.254 |
|
max |
31.96 |
1.258 |
||
|
7 |
Check rail gauge |
min |
31.98 |
1.259 |
|
max |
32.08 |
1.263 |
||
|
8 |
Crossing flangeway (straight track) |
min |
1.00 |
0.039 |
|
max |
1.08 |
0.043 |
||
|
9 |
Over check rail faces |
min |
30.85 |
1.215 |
|
max |
31.08 |
1.224 |
||
|
10 |
Crossing flangeway – effective flange |
min |
0.34 |
0.013 |
|
max |
0.42 |
0.017 |
||
|
Verification of Clearances |
||||
|
11 |
Minimum check rail gauge – (maximum back-to-back + one effective flange) |
= 31.98 – (31.30+0.66) = 0.02 minimum clearance |
||
|
12 |
Minimum track gauge – (maximum back-to-back + two effective flanges) |
= (31.30+1.32) = 0.38 minimum clearance |
||
|
13 |
Minimum back-to-back – maximum over check rail faces |
= 31.20 – 31.08 = 0.12 minimum clearance |
||
