The coach parked here in front of the DAF Museum is a unicum, a Curbside Classic Sole Existing Exemplar. It’s a 1970 DAF SB200 bus chassis with a one-off body from the Belgian coachbuilder Jonckheere. Custom-built for Philips, the Dutch technology company.
The coach was specifically built to test a Philips-Stirling vehicle engine, mounted in the rear of the DAF chassis. On its roof the engine’s heat exchanger/cooling unit. The driving force behind the project was Frits Philips (1905-2005), the president of the company from 1961 to 1971.
Frits Philips was convinced that a Stirling engine eventually could become a real alternative to the internal combustion engine. Unfortunately, some major problems occurred during the field-tests.
The starting procedure turned out to be rather problematic. But above all, the Stirling engine didn’t have the qualities to run at variable speeds, which is of course an absolute necessity in any road vehicle.
Alas, the Philips-Stirling had to removed from the chassis and the coach was retrofitted with a trustworthy 6-cylinder DAF diesel to keep it on the road. Nevertheless, Philips-Stirling engines certainly functioned successfully as a stationary power unit. Highly efficient, very clean, no noise.
The Philips company worked on the Stirling engines from the late thirties to the late seventies and improved them significantly. They were good enough for the NASA, for example.
This is clearly a VIP-coach interior, equipped with all the luxury and goodies that were available when it was built. All in all, the coach is a great piece of industrial heritage, even without its original engine. And with that conclusion we end the 2016 DAF Museum Days Bus & Coach Tour.
(A more detailed read about the Philips-Stirling engines can be found here, included the Philips Type 4.235 Stirling vehicle engine)
1970 DAF-Jonckheere (the conventional coach)
Was DAF thinking that a heavy version of their CVT would enable the constant speed engine? Seems reasonable. Dynaflow Buicks and CVT Justys seem to run at a nearly constant engine RPM.
DAF only supplied the bus-chassis, they were not involved in the Stirling-project.
DAF = Variomatic
VDT (Van Doorne’s Transmissie) = CVT
Hub van Doorne (The D in DAF, together with his brother Wim) retired in 1965 and kept on working on the further development of the Variomatic. Initially in a shed behind his house, later on he founded VDT. His work resulted in the CVT as we know it now.
DAF never built transmissions for their trucks. Although there was this below, the small DAF Pony truck or tractor with a dual-belt Variomatic.
Most of the DAF trucks Ive driven have 18 speed Roadrangers by Eaton Fuller.
ZF transmissions in Europe.
“the Stirling engine didn’t have the qualities to run at variable speeds, which is of course an absolute necessity in any road vehicle.”
They had to build a costly prototype before they noticed that? This is what white-paper research studies are for! And computers were available by then, too. Perhaps some engineers pleaded with Mr. Philips to no avail?
And to think, Jonckheere used to do coachwork for cars too. One of their notable creations is the Round Door Rolls Royce which is in the Petersen Museum collection
https://www.heacockclassic.com/articles/the-round-door-rolls-1925-rolls-royce-phantom-i-jonckheere/
I know it’s off topic and I apologize, but Jonckheere doesn’t pop up very often in blog posts.
Van den Plas, another Belgian coachbuilder. We all know how that name ended…
Interesting that his company name is Willy van den Plas. For a coachbuilding firm, I would have thought Willem, like the English William – sounds more ‘dignified’ in English than ‘Billy’. I know several Willems, and I wouldn’t call them Willy. Or is Willy a separate name in Holland?
Wim, Wil, Willy and Willie all originate from Willem (Wilhelm in German, William in English and Wilhelmus in Latin).
Wim is a man, Willie or Willy is a man or a woman.
And then there are Willemien and Willeke, women (Full name of the female form is Wilhelmina).
If Wim is young (a kid) or a short guy he’s often called Wimke.
Willems, Willemse and Willemsen are last names.
That should explain it.
They go a long time with little heat. Ran a model almost an hour on a cup of coffee. Guess speed is important but seems it could be overcome with a hybrid system. Lack of torque seems a bigger problem but same possible solution. Electrostirling anybody. .
Here’s Frits Philips with a retirement-gift, a lawn mower with a 10 hp Stirling engine (Photo courtesy of Stichting Eindhoven in Beeld).
I imagine the Stirling would work just fine in that application.
Fascinating find Johannes – really enjoyed the series. Jim.
1970?
Wow, that bus looks too modern to be that vintage… I would’ve easily mistaken it to be a 2000+, or a 1990’s bus, at least.
The city buses in the US look like and are 80’s relics. At least, the ones running in New England are.
Stirling engines do occasionally get used in stationary generators. My recollection is that the Italian Antarctic research station at Dome C used one.