21. However, simply increasing the boiler pressure would have made an engine more powerful without increasing its efficiency. 22. Their boiler pressure setting was reduced from. 23. All were rebuilt with new boilers and extended smokeboxes from 1918 and some had increased boiler pressure . 24. Boiler pressure was 100 pounds of steam and the engine turned 92 revolutions per minute at top speed.25. The boiler pressure was rated at. 26. Several locomotives were later given boilers with the higher boiler pressure and were then classified as G 4.1. 27. They were described as " free steaming ", meaning they could maintain boiler pressure regardless of throttle setting. 28. Over time the boiler pressure was upped, and 36 inch diameter cylinders replaced the original 42 inch cylinders. 29. With such a setting, when the exhaust opens, the steam in the cylinder is near full boiler pressure . 30. For steam locomotives, additional parameters such as boiler pressure and fire state can be set, monitored, and controlled.
