Atchison Topeka & Santa Fe Engine 2926 was one of 30 oil-burning Northern 4-8-4 P2900 Class steam locomotives built by the Baldwin Locomotive Works in Eddystone, just south of Philadelphia, Pennsylvania, between 1943 and 1944. This engine received the builders plate number 69814 and was placed in service on May 9, 1944.
AT&SF 2926 was in service until December 12, 1953. On October 29, 1956 the engine and tender were donated to the City of Albuquerque, New Mexico and placed on display in Coronado Park.
The Engine, Tender and Caboose were purchased by the New Mexico Steam Locomotive & Railroad Historical Society from the City of Albuquerque on July 26, 1999 for eventual restoration. That restoration is ongoing today and it is hoped that the engine will finally be operational again in 3-5 years.
- Q: How old is 2926?
A: Again, 2926 was originally built and placed in service on May 9th, 1944 which would make it 77 years old today.
- Q: How big is 2926?
A: That depends on what you mean by big. Together, the engine and tender are approximately 121 ft long.
- Q: How much does it weigh?
A: The locomotive weighs 510,150 lbs. and the tender weighs 464,700 lbs. fully loaded with fuel and water.
- Q: How does it work?
A: Oil is burned in the firebox to heat the water in the boiler and make steam. The steam is piped to the cylinders to drive pistons back-and-forth. The pistons are connected to the steel pins on drive wheels by rods. When the pistons move back and forth the rods transmit that force to the drive wheels making them rotate
See some excellent animations by www.mekanizmalar.com of how the internals of a Steam Locomotive work at the bottom of this page.
- Q: How powerful is the 2926?
A: There are three measures of power: tractive effort, draw bar pull, and horsepower.
Tractive Effort: The starting tractive effort generated by the drive wheels is listed in all company documents and specifications as 66,000 lbs. However, that figure is thought to be little low. The real tractive effort when starting is estimated to be closer to 70,000-74,000 lbs.
Draw bar Pull: The actual pull exerted at the tender coupler (and therefore available to pull the train) ranges between 68,000-72,000 lbs. This is based on test data obtained from a similar Santa Fe 4-8-4 (#3766). The difference between estimated tractive effort and actual measured draw bar pull is the amount of tractive effort (several thousand pounds) needed to start the dead weight of the tender.
Horsepower: Horsepower varies with speed. Maximum horsepower is developed between 35-65 mph. Testing showed draw bar horsepower (measured at the coupler on the rear of the tender and available to pull the train) as 4,590 at 40 mph. The locomotive was actually producing more horsepower (500-800 more), but some power is consumed moving the engine and tender at that speed. As speed increases, more horsepower is needed for the engine and tender just to maintain the higher speed, and less is available to pull the train.
- Q: How fast could 2926 go?
A: Nobody really knows. It was designed for 90 mph operation. That doesn't mean it couldn't go faster. It was upgraded (as were all 2900 class engines) between 1946-48 with light weight roller bearing rods to increase the design speed to 100 mph and in passenger service there are lots of stories of speeds well over the century mark. But documented runs in excess of 100 do not exist. This is because running over 100 mph exceeded established speed limits and could get engineers in trouble. However, when running late and with a head nod from management, crews did exceed 100 mph and occasionally (if the stories of old timers are to be believed) exceeded 110 mph. The locomotive's design, wheels, rods, bearings, pistons, lubrication, etc. should have been capable of the machinery speeds required to exceed 120 mph or more.
Thanks to Dr. S. Ersoy (www.mekanizmalar.com) for giving permission to imbed the following YouTube animation which depicts how the internals of a Steam engine work. AT&SF 2926 works fundamentally in the same fashion, not withstanding the fact there are subtle differences in our wheel arrangement, exact plumbing, etc.
Be sure to also check out the interactive animation at WWW.MEKANIZMALAR.COM of the basic Walschaerts Valve Gear mechanism that is used in many steam locomotives.