The First Mountain-climbing Steam Locomotive on Alishan – the Return of SL-21, a Must-See for Railway Enthusiasts

By MOOK Scenic Spots, compiled & reported
 
The first mountain-climbing steam locomotive on Alishan, SL-21, was returned to the Chiayi Depot of the Alishan Forest Railway on July 23 from Chiayi Park. It will be restored using the original coal-burning method and will resume operations to bring back its former glory through active preservation.

In 1912, when the Z-shaped section of the Alishan Railway was being developed, the existing 18-ton Shay steam locomotives could not handle the steep gradient of up to 1 in 66.7. As a result, 28-ton Shays were purchased from the American company Lima and numbered 21, making it the first 28-ton steam locomotive. In total, 12 locomotives of this 28-ton class were gradually introduced.

The 28-ton mountain-climbing Shay steam locomotive SL-21 features three vertical cylinders to shorten the body length, a bevel gear drive to enhance power transmission, and telescopic axles with universal joints that allow flexible turning on curves. Its special design is ideal for Alishan’s mountainous routes, which feature numerous curves, tunnels, and long gradients. It is a precious heritage asset in world railway history. During the logging period, SL-21 was stationed at the Fenchihu depot and responsible for transporting timber from Alishan. After being decommissioned in 1975, it was loaned to Chiayi Park for display.

Forty-four years later, the exterior of the SL-21 steam locomotive has rusted and parts have been damaged. To ensure the smooth lifting operation of the SL-21 steam locomotive on Alishan, the Forestry and Cultural Heritage Bureau sent personnel on July 17 to first remove the drive shaft and clean and lubricate the axle and power components. This facilitated placement on the track afterward, reducing travel resistance during train coupling and operation, and protecting the steam cylinders.

The empty weight of the SL-21 locomotive is approximately 25 tons. However, considering safety and to avoid damaging park facilities, a 200-ton crane and several flatbed trucks were deployed, along with a specially made lifting frame constructed from original steel rails by the Forestry and Cultural Heritage Bureau. After over two hours of work, it was finally lifted onto the Pingjiao intersection on Weixin Road.