Triplex locomotive

All triplex locomotives built were of the Mallet type, but with an extra set of driving wheels under the tender.

[citation needed] The triplex locomotives were of the Mallet type, but with an extra set of driving wheels under the tender.

As only half of the exhaust steam went through the blast pipe in the smokebox, the draft in the firebox and the heating of the boiler was poor.

Westing[1] gives a figure of 160,000 lbf (710 kN) in compound mode and seems to indicate that it was the largest tractive effort for any locomotives up to the mid-1910s.

The triplexes could also be considered the largest tank locomotives ever built, as the tender also had driving wheels and thus contributed to the traction.

The problem of diminishing adhesion of the tender unit as water and coal was used; was not a significant factor or design flaw, as the rear engine as designed was not to produce as much adhesion than the front and middle engines, by adjusting the steam lap;[4] which compensating for the usage of coal and water.

Also, pusher locomotives had frequent opportunities to take on additional fuel and water as they were not not "line haul" assignments.

[5] The reason for this was the poor performance of the boilers due to the lack of exhaust draught from the driving wheelset under the tender.

[6] The Erie locomotives were used as helpers on the Susquehanna Hill also known as the Gulf Summit, near Deposit, New York, on the Southern Tier Line.