Gallery opened: March 2001 Previous update: 3 Mar 2003 Updated: 28 July 2020 Drawings added

Geared locomotives had perfectly good reasons for their apparently eccentric design. If adhesion is in short supply, one way to get maximum tractive effort is to make sure that ALL the wheels are driven.

Left: The Heisler geared locomotive 1898 The Heisler had a V-twin engine slung under the boiler, driving fore-and-aft shafts on the centre-line. It takes it's name from Charles L Heisler, American locomotive designer. One cylinder head is visible below the steam (rearmost) dome.

Left: Another Heisler at rest. It is clear that the V-twin engine configuration limits the boiler diameter. The steam supply pipe from the steam dome to the cylinder is clearly visible. The pipe running forwards presumably carries the exhaust to the blastpipe in the smokebox.

Left: Side elevation of a Heisler. The centre shafts running to the forward and back bogies are visible below the boiler.

Left: Transverse section of a Heisler: 1898 The cylinder exhaust reached the smoke-box blast-pipe through a pipe that can be seen at the 8 o'clock position on the boiler. Source: The Engineer for 21 Jan 1898, p65

Left: The shaft and gearing of a Heisler: 1898 Note that the front and rear shafts both used two universal-joints to prevent variations in angular velocity; one universal joint alone is not constant-velocity. The only gear reduction was in the bevel gears on the axles. Source: The Engineer for 21 Jan 1898, p65

Roughly 625 Heisler locos were produced, of which some 35 still exist. Eight of these are believed to be currently operational.

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