Equipment Information

The widespread use of propane as a motor fuel began in the 1940s, although it had been used experimentally since the 1920s. One of its largest advantages at the time was that, as a byproduct of natural gas processing and petroleum refining, it was quite inexpensive; most of the cost was in its handling and transportation. It is one of the easiest fuel gases to handle, because its high boiling point enables the use of relatively low pressures to liquefy it at room temperature. In comparison, natural gas cannot be liquefied except at very low temperatures, and thus practical quantities for motor fuel use require heavy tanks to contain the very high pressures needed.

Propane tends to burn very cleanly in an engine, and does not dilute crankcase oil as gasoline or diesel fuel can. It also does not require a complicated carburetor. Propane’s primary disadvantage lies in the fact that it is heavier than air, and a leak will tend to pool in low places instead of dissipating. This fact has caused large explosions, including at CTA’s Kedzie Garage in 1969. Propane buses also tended to have less accelerating power than similar diesel buses.

CTA began using propane-fueled buses in 1950, and many of its electric streetcar routes were converted to propane buses. In total, CTA operated 1,700 propane buses, more than half its fleet. Bus 8715 was built as part of CTA’s final propane bus order; rising costs for the fuel removed its single largest advantage, and CTA opted to purchase diesel engines on all future orders. Most of the propane fleet was retired in 1973, although the 1963-built buses (including bus 8715) remained in service until the end of all propane service in 1976.

First preserved by CTA, it was acquired by the Chicagoland Historical Bus Museum in 2003, and was donated to IRM when they closed in 2011. It is nearly complete, but has not been restored to operation.

Builder: Flxible
Year Built: 1963
Model: Model F2P-401
Seats: 50
Length: 40ft 3in
Width: 8ft 6in
Height: 9ft 10in
Weight: 21130 lbs
Engine: Fageol-Twin Coach FTC-200-69
Transmission: Spicer M-184
Description: Motor Bus
Arrived: 2011
Condition: Complete / unrestored / not operational

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