At the time, the advantages to be gained by superheating were gradually becoming apparent as the most practical means of improving engine power and efficiency.
Superheating was considered the greatest step forward regarding improved performance and efficiency in steam locomotives.
The claims that superheating could effect a saving of from 10% to 20% in fuel and from 15% to 25% in water were not unfounded and were even improved upon in later years.
Experience with the Class B America D proved, when compared with the saturated steam Class B Hendrie D, that it was more economical in fuel and water consumption.

The locomotive's superheater was of the Cole type, which was somewhat similar to the Schmidt system, except that the Cole type had two headers arranged at either side of the smokebox instead of one at the top.
Each of the fifteen 5 ¹⁄₄ inches (133 millimetres) diameter boiler flues contained four lengths of seamless steam pipes of 1 ¹⁄₂ inches (38 millimetres) outside diameter, arranged in double pairs which were connected at the back ends by return bends and with the two pairs connected to each other at the front by another return bend.
This forced the steam to traverse the entire four pipe lengths before entering the steam chests.
The two free front ends of each such foursome of pipes were bent around to meet the steam headers.
This design of superheater produced a superheat of from 175 to 250 degrees Fahrenheit (79 to 121 degrees Celsius) above saturation temperature.

The passage of gases through the large flues and around the superheating pipes was controlled by a damper, which was automatically operated by a steam cylinder connected directly to the steam chest.
When the throttle was opened, the pressure in the steam chest would open the damper, which would be closed again by a counterweight when steam was shut off.
Superheater dampers were used for many years until it was determined that damping was unnecessary, since the life of the superheating elements was not increased appreciably by their use.
On the SAR, the use of superheater dampers was discontinued c. 1924.
At the time, the advantages to be gained by superheating were gradually becoming apparent as the most practical means of improving engine power and efficiency. Superheating was considered the greatest step forward regarding improved performance and efficiency in steam locomotives. The claims that superheating could effect a saving of from 10% to 20% in fuel and from 15% to 25% in water were not unfounded and were even improved upon in later years. Experience with the Class B America D proved, when compared with the saturated steam Class B Hendrie D, that it was more economical in fuel and water consumption.
The locomotive's superheater was of the Cole type, which was somewhat similar to the Schmidt system, except that the Cole type had two headers arranged at either side of the smokebox instead of one at the top. Each of the fifteen 5 ¹⁄₄ inches (133 millimetres) diameter boiler flues contained four lengths of seamless steam pipes of 1 ¹⁄₂ inches (38 millimetres) outside diameter, arranged in double pairs which were connected at the back ends by return bends and with the two pairs connected to each other at the front by another return bend. This forced the steam to traverse the entire four pipe lengths before entering the steam chests. The two free front ends of each such foursome of pipes were bent around to meet the steam headers. This design of superheater produced a superheat of from 175 to 250 degrees Fahrenheit (79 to 121 degrees Celsius) above saturation temperature.
The passage of gases through the large flues and around the superheating pipes was controlled by a damper, which was automatically operated by a steam cylinder connected directly to the steam chest. When the throttle was opened, the pressure in the steam chest would open the damper, which would be closed again by a counterweight when steam was shut off. Superheater dampers were used for many years until it was determined that damping was unnecessary, since the life of the superheating elements was not increased appreciably by their use. On the SAR, the use of superheater dampers was discontinued c. 1924.
South African Class 3A 4-8-2