10 December 2010

LGB rack

Climbing grades with LGB rack

HGe 2/2 FO 24
The ultimate solution to grade problems is a rack railway. Regular LGB trains, like most real trains, use the "adhesion" between the wheels and rails for traction. However, rack railways (sometimes called "cog" railways) can exceed the limits of adhesion, climbing grades as steep as 48%. Rack locomotives are equipped with a large drive gear, called a "cog." That gear meshes with a "rack" mounted on the ground between the rails. Rack railways can be found in mountainous areas around the world, both standard and narrow gauge.

ABT rack
The LGB rack railway system is modeled after the "Abt" prototype system (developed from the swiss engineer Roman Abt around 1880), which is used by the Furka Oberalp Bahn (FO) and many other rack railways. LGB rack locomotives can operate on grades of up to 25%, climbing 250 mm for every 1000 mm of horizontal distance.

Snowdon Mountain Railway. A typical wheelset on display at Llanberis. (A.M.Hurrell)

LGB rack

The LGB rack program includes rack locomotives along with some special rack accessories:

- 10210 Cog Rack, 300 mm, 12 pack
- 10220 Cog Rack Holder, 24 pack
- 64462 Rack Loco Coupler Hooks, 8 pack

The 10210 Cog Racks (or "rack rails") are easy to install. Using the 10220 holders, they can be fitted into both straight and curved LGB track sections, and the rack sections can be installed in existing layouts without removing the track. To install a cog rack, install the holders between the track ties. The distance between the holders will vary, but in curves, the distance between holders should be less than 150 mm (5.9 in). Once the holders are in place, snap the racks into the holders from above. The holders will latch to the rack and to the track.

LGB rack
LGB rack tips
To avoid abrupt transitions, use several short straight track sections, like 10150 sections, at the beginning and the end of a steep section. Slightly bend each joint vertically to create a smooth transition.
For overhead catenary operation on steep sections, use the 56300 tilting catenary mast. The masts should be spaced closer than on level track.

To avoid accidental uncoupling, 64462 coupler hooks are recommended for rolling stock used on rack sections. Also, "symmetrical" coupler hooks should be installed on both ends of all rolling stock. LGB rack locos can be used on rack sections and regular "adhesion" sections.

When climbing or descending a steep section, the rack loco should always be on the downhill side of the train. Real rack railways follow this safety procedure, and LGB rack operators should abide by the same rule.

Here a selection of (discontinued) LGB rack locomotives

LGB 20471
LGB 20471
Ballenberg Rack Steam Loco, 1067

LGB 21470
LGB 21470/21471
SBB Brünig HG 3/3 Rack Steam Loco, 1068

LGB 24460
LGB 24460
FO Rack Electric Loco, HGe 2/2 24

LGB 70246
LGB 70246
Zugspitzbahn Rack Train Set


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