This is before ACF-Brill spun off Hall-Scott in 1954. By that time, ACF-Brill was getting out of the bus business, run off by GM Truck & Coach's highly successful rear-engined diesel coaches. Later, Hercules bought Hall-Scott and shut down this plant. Last OEM user of Hall-Scott engines was Crown Coach in LA, which fully converted to diesels by 1965. Hall-Scotts were good engines, but were horribly inefficient. A Brill IC41 using a Hall-Scott 190 got around 2-3 MPG on the road, while a GM PD-4103 with a GM 6-71 got 7 or better with the same payload. The choice for Trailways was obvious...go diesel or fold. The Hall-Scott powered Brill was faster...but had horrid brakes. I know...I drove both models. Judging from the models in production and the audio equipment and credits, I'd date this program from 1950-51, probably produced by ABC-owned KGO. The two main things that sunk Hall-Scott? Archaic production methods and their failure to build a useful diesel engine that didn't explode. (The Model 140 disaster.) Also...note the lack of counterweights on that archaic crank! And only three mains!Hall-Scotts were smooth runners...only by virtue of their excessive mass of their blocks. They'd run forever...if not pushed too hard. Overrev one on a grade, though, and you'd break a crank quickly. The rest of the industry had moved on; Hall-Scott was still stuck in the 1920s.
Hercules quit building Hall-Scott engines in Canton some time between 1968 and 1970, but Crown Coach put 3 Model 590 engines in 1967 buses and a few 1091s in Firecoaches until 1969(serial numbers on all are available, thanks to Crown records). The number of engines produced was limited by the mid-60s, though. New info found 2021 - Gillig put 2 Model 590 engines in 1967, and one last one in 1968.
DesertTBoB: In saying "horribly inefficient", you are not being fair. Hall Scotts were gasoline engines. GM-6-71's were 2 stroke diesel. Thermodynamic efficiency (conversion of chemical energy in fuel to mechanical output) of almost any gasoline engine is around 22 to 27%. Thermodynamic efficiency of almost any diesel engine is 45% plus. That's at high power settings - as a gasoline engine is throttled back for cruising, it's efficiency falls off faster than it does in a diesel racked back. Gasoline engines are cheaper to make, much lighter, and cheaper to maintain (especially until the advent of low sulfur fuel cut back the wear in diesel engines), so when gasoline was cheap, a gasoline engine could be cost effective in spite of double or more the fuel consumption. That's why gasoline has always been dominant in cars.
Less efficient diesel engines exist as well. Typically a 1920s - 1950s gas engine will have between 4:1 and 8:1 compression ratios, while modern engines from the 1990s forward achieve 10:1 (147 psi), approaching 11:1. In turbocharging applications, 9:1 is acceptable because the last:1 is delivered by variable boost. Low compression diesels are as low as 14:1, but typically 16:1 being more common and suitable for turbocharging. In naturally aspirated forms, 21:1 to 25:1 (600 psi) are typical for high compression, highly efficient diesel engines. The high compression of these engines means there is little margin for turbocharging. In the 1950s, aviation gas engines were commonly 6:1 with exhaust-driven turbochargers and some also featured an axially driven centrifugal superturbocharger. Today we just call them superchargers.
Narration is wrong as Hall Scott engines DID NOT power PT Boats !!! The US Navy use only the Packard M2500 series engines in all PT Boats !!! Hall Scotts engines did power the smaller air sea rescue boats !!!
