The car is based on an
Alfa Romeo RM chassis with the normal 2-litre, 4-cylinder RM engine. The
track mechanism was built using Citröen patents under. The front wheel
hubs are marked with the Citröen gear motif. The drive system is based
on that used in the Citröen Kegresse but incorporates the original RM
transmission brake.The four-speed gearbox feeds via a propshaft into
another enormous transmission case, housing a second gearbox with a dual
range. The concept of the track laying system was developed by Adolph
Kegressewhen Technical Manager for Czar Nicholas II as early as 1910. By
1920, assisted by Jacques Hinstin, Kegresse was running the Chenilles
department for André Boas and André Citröen at the Citröen Gear Company.
In 1921 three Kegresse Citröens climbed the Lautaret andcrossed the Mont
Genevre Pass clearly showing their ability over snow.
This RM and its track gear
both exhibit early chassis and licence numbers. The RM chassis numbers
run from 1923-1924 and are listed as 12001 – 12265; it is known that the
early numbers were restricted to prototypes so ‘12023’ could date this
vehicle tovery early in 1924 or possibly even late 1923. At the
Rétromobile show in 2005, two Sahara type Citröens were on display, one
with a trackmechanism licence number of 425 thereby showing how early
the RM’s track gear is.