2. Leaf springs

The production process of leaf springs (Figure 8) is similar to that of helical springs, as shown in Figure 16, with the same rust prevention, testing, and other post-processing devices.


**Figure 16.** Flowchart of sheet metal spring production line.

The first step is the billet shearing, where the billets are sheared to the appropriate length with a steam hammer (A32).

The second step is heating, where the sheared leaf spring billets are delivered to the coke furnace (A46) in order to heat the billets until they are soft enough to bend.

The third step is bending and shaping, where the softened billets are bent and shaped by a spring forming machine (A12). The bending length is controlled by a screw on the bender; moving the corresponding nuts by turning the screws with the handle to bend the leaf billets, as shown in Figure 17.

**Figure 17.** Bending, shaping, and assembling. (**a**) Spring forming machine (A12), (**b**) strapping machine (A05-2).

The fourth step is quenching, where the formed leaf springs are immersed in a quench tank (A15) to rapidly cool the spring steels.

The fifth step is tempering. The billets are forging to temper themselves.

The sixth step is assembling. A leaf spring is made up of many steel plates with different lengths, all of which are made through the above procedure, and holes are drilled in the center of all plates. Finally, the leaf spring stacks are tightened by a strapping machine (A05-2). An old photo (Figure 18a) shows the assembly of the leaf spring with a specific device. However, this device cannot be found in the forging workshop nowadays. Figure 18b shows both the helical and leaf springs made in the field in 1956.

**Figure 18.** Manufacture of the leaf spring (1956) (Courtesy of the Taiwan Railway Administration). (**a**) Assembly, (**b**) springs made in the forge shop.

#### *3.2. Forging Area*

Forging is a manufacturing process to shape billets into machine parts by hammer strikes. Five forging machines in different sizes still remain on the site of the forging shop in Taipei Railway Workshop, and there are many heating furnaces, cranes, pliers, and clamps in the forging area.

In the first step, the billets are clipped with clamps and put in a heating furnace, then the billets are heated to 500–800 ◦C, in order to soften the steel for shaping. For heavy billets, cranes are used to hang the billets, which convey billets back and forth between heating furnaces and forging machines.

The second step is forging, where parts are forged by steam hammers, forging machines, or workers with hammers, depending on their types. Figure 19 shows the use of steam hammers in the forging workshop in 1956, and it can be seen that many workers cooperated with each other for forging.

**Figure 19.** Forging (1956). (**a**) Two-ton steam hammer (A45) [2], (**b**) one-ton steam hammer (A32) [2].

There are five forging machines preserved in the forging shop. Inferring from No. A45 large steam hammer and No. A43 steam hammer with a large crane, they are used to process large objects. Due to low weights, No. A32 and No. A28 steam hammers are used to process small parts. Unlike the four abovementioned steam-driven machines, the other forging machine (A42) is electric-driven and used for mold forging. Figure 20 shows a set of machines for forging manufacture.

**Figure 20.** Current conditions of steam hammers (A45) and cranes (A47).

Among the five forging machines manufactured in Britain in 1889, the No. A32 steam hammer is the oldest machine in the Taipei Railway Workshop and has special research, preservation, and exhibition values. Figure 21 shows the words on the body of the steam hammer, including three important pieces of information. The first one is Rigby's Patent, the second is the production place in Glasgow, and the third is its production number (No. 941). According to literature, this steam hammer was manufactured by Glen & Ross LTD., a British company founded in Greenhead, Glasgow, Scotland in 1856. As a steam hammer manufacturer of considerable scale, the company had so many employees that it was able to meet the growing number of domestic orders and huge demands for export trades in the 19th century [15,16].

**Figure 21.** Steam hammer manufactured in 1889 (A32).

In the late 19th century, Taiwan began to introduce western machinery and made its own weapons, such as guns and ammunition, and developed its railway system. Under this background, officials at that time had sufficient motivation to buy steam hammers; however, according to the literature now collected, no direct evidence shows that the steam hammer made in 1889 came to Taiwan. Data collection and verification of this steam hammer are also the important goals of the following work.
