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acparker 04-10-2018 06:05 PM

Rootes(Commer) TS3 and similar engines
Not wanting to continue hijacking MorphDaCivic's Achates thread, I have started this one to discuss single-crankshaft, rocker-arm, opposed-piston engines. The best known of this type was the TS3 built by Rootes(Commer).

I will attempt to move relevant posts, or content thereof, from that thread as cleanly as possible.

In the meantime, a quick internet search using the tags revealed two Achates patents on the subject, US9359896 and US20110186017, both dated 2010.

Quoting the abstract from US9359896, "An opposed-piston engine with a single crankshaft has a rocker-type linkage coupling the crankshaft to the pistons that utilizes a rotatable pivot rocker arm with full-contact plain bearings. A rocker-type linkage utilizes a rotatable pivot bearing with an eccentric aspect to vary translation of piston linkage along the axial direction of a cylinder, which shifts the top dead center (TDC) and bottom dead center (BDC) locations of a piston so as to change the volume of charge air compressed during the power stroke."

There are other related Achates patents.

They also cited in their prior art a patent by George Henry Enderby, GB183501 (A), dated 1922-08-01. This is the oldest patent on the subject that I have located thus far, though I seem to remember a drawing going back as far as about 1900.

Daschicken 04-10-2018 06:48 PM

My only experience with opposed piston engines is with the Rolls Royce K60 engine in a FV 432 APC. It does have two crankshafts and six cylinders, so its not quite the same as your rocker arm engine.

It chooched when I pressed the go pedal, and it sounded pretty normal to me. ;) Don't know what else to say.

acparker 04-10-2018 09:33 PM

Here are relevant posts (with some editing) from " New Boxer Engine Pickup get 37 MPG":

Originally Posted by acparker (Post 565549)
... Opposed-piston engines have been around for a very long time. Chrysler killed the Rootes/Commer TS3 and TS4 opposed-piston engines when it purchased Rootes in 1968.

The rocker-lever design used by Rootes was not original to them. Sulzer, Olds, and the French manufacturer, MAP, built similar engines at least ten years earlier. These engines were compact and powerful. They had their quirks, but were generally held in high regard by their operators and the mechanics who kept/keep them going.

Sulzer built primarily stationary engines (ZG9). There are Swiss fortresses with Sulzer engines running generators.

Ransom Olds also built stationary and marine engines through the Hill Diesel Engine Company. I have seen reference that Hill built licensed Sulzer engines, but Olds held patents on a rocker-lever engine as early as 1937.

MAP ran a four cylinder version of their standard two-cylinder tractor engine (2H88) in Le Mans in the late 50's [Correction. It ran in the 1950 Le Mans]. In Italy, licensed MAP engines, built by Breda-Isotta Fraschini (FB4R) were also put into Ansaldo Fossati tractors.


Originally Posted by acparker (Post 565691)
There is a patent, US2809614, assigned to Continental Motors (now owned by the Chinese government) that addressed stress issues with the rocker-arm (the term, rocker-lever, seemed a bit off, may have been a google translate thing) designs. They were looking at it for aviation use. Obviously, nothing came of it.

I think the rocker-arm designs may have made a more compact engine than the two-crankshaft designs -- or not. It may have had less friction than gear towers. I haven't read any comparisons.

There is a patent, US2134811, by H.D. Church that drives two sets of rocker-arms off of one crankshaft to two banks of cylinders. It was never produced, as far as I know.

R. Laraque describes improvements to his earlier rocker-arm designs for MAP in US2530884. The earliest patent I found for him was on Espacenet, FR812528 (A).

The Olds patent is US2099371A.

The oldest Sulzer patent I could locate can be found on Espacenet, GB449802 (A). This puts Laraque, Sulzer, Church and Olds putting patents out close to the same time ('34-'37), with the edge to Olds -- maybe. I am fairly certain there were rocker-arm designs that predate those four.


Originally Posted by acparker (Post 565712)

You can see a video of the only working TS4 prototype in existence here:

For comparison, a TS3:

For general amusement, a stitched together Leyland sports car with a TS3 (purported to go 140 mph and get 30 mpg):

Here you can see a MAP 2H88 in "working" order:

Here is a website describing two Sulzer 4ZG9 powering a swiss fort, the first is a flash video (in German) and the second has photos, schematics and further details (also in German, but you can try google translate):

Festungsmuseum Heldsberg - CH-9430 St. Margrethen*-*Technik
Festungsmuseum Heldsberg - CH-9430 St. Margrethen*-*Notstrom-Dieselgeneratoren


Originally Posted by cRiPpLe_rOoStEr (Post 565979)

I'm aware of at least one opposed-piston Diesel aviation engine project, but it's not from Continental and resorts to a two-crankshaft design.

I'm not so sure about the extent of an eventual compactness that could be inherent to the rocker-arm design with a single crankshaft, but maybe it would lead to an easier packaging for general aviation as a drop-in replacement to the old opposed-cylinder gassers that are still mainstream.


Originally Posted by acparker (Post 566011)
I could not say that the single-crankshaft rocker-arm design is superior to other configurations, but I think it is significant that there were a cluster of patents in the mid to late '30's that resulted in two relatively successful designs being manufactured, Sulzer's ZG9 and MAP's 2H88 (Olds did manufacture some engines, but it is undetermined if they were a licensed Sulzer design, or based on his own patent), followed some twenty years later by the Rootes (Commer) TS3 which proved the most successful and most widely distributed.

Commer pursued this configuration because they wanted a low, compact engine that could be used in a cab-forward truck. The two-crankshaft opposed-piston designs are either very tall or very wide, and conventional diesels of the era were very large and very heavy.



Originally Posted by cRiPpLe_rOoStEr (Post 566094)
The first single-crankshaft opposed-piston engine I heard of was the Rootes TS3 anyway...

In the end it was a great engine, not just relatively compact but, apart from the particulate matter emission, it actually fares better than many electronically-governed Euro-3 engines fitted to vehicles with a comparable load capacity.


Originally Posted by RustyLugNut (Post 566131)
I am enjoying this thread. Thanks to acparker for the links to these wonderful engine side roads.

I remember seeing the Roots TS3 running around our neighborhood. I've always wanted to grab one and refit a more capable fuel system. I feel two strokes are dismissed as being too noisy and dirty without digging deeper into the design.

The only real problem is the oil that can slip by the fuel/exhaust ports. That can be minimized. An extended stroke TS3 can allow us to provide a head with an intake valve system reducing that source of oil bypass. Mapping of trapped exhaust allows us to provide natural EGR as well as additional EGR for reduced NOx. High pressure common rail injectors will reduce exhaust coking problems. Current clean diesel exhaust after treatments would make it viable for even the ultra strict California market.

Just dreaming out loud.


Originally Posted by cRiPpLe_rOoStEr (Post 566192)
The only time I saw a TS3-powered truck, it was parked under a bridge in the Brazil-Uruguay border. Well, I wasn't even able to figure out if it still had the stock engine or if it had already been repowered with some Brazilian 4-stroke (the Mercedes-Benz OM352 had been a popular alternative for engine swaps in Brazil, Argentina and Uruguay).

Since I got to know about the TS3 I wanted to get one and fit into some Chevy full-size truck.

When it comes to 2-strokes, nowadays most people seem to forget the Diesel ones and only remind spark-ignited applications. Well, at least most 2-stroke Diesels resorted to an oil recirculation lube system, which makes it easier to implement some emission controls which became mainstream such as EGR.

The absence of a cylinder head is actually a desirable feature, since there is a smaller surface for heat losses through irradiation, thus the engine can convert more energy into motion instead of just waste it.


Originally Posted by acparker (Post 566262)
... here is some information about MAP's 1950 Le Mans car (click on appropriate flag in upper right corner for English version):

Equipa 1/1950

Check out the aerodynamics on the mid-engine design. The engine was a 4 cylinder version of MAP's 2H88 used in tractors. It also set several records in another chassis at the Autodrome de Montlhéry. There is an old article about it here (please note that there may be some security issues with the site, or ads embedded in it, and url's in the text):

LES RECORDS DE LA MAP DIESEL - blog pour la mémoire de l'autodrome

cRiPpLe_rOoStEr 04-11-2018 06:28 AM

It's quite surprising to figure out that even Achates has some patents related to this design. Well, even though the dual-crankshaft design may work well and eventually be easier to increase the stroke, I must confess I'd still feel more comfortable dealing with a single-crankshaft engine...

acparker 04-11-2018 04:23 PM

Achates' current focus may be based on its affiliation with Fairbanks-Morse and Cummins.

Fairbanks-Morse is familiar with, and known for, the dual-crankshaft design and would be interested in a downsized model for truck use.

It was a (supposedly inferior) Cummins engine that replaced the TS3. Institutional prejudices can linger for decades. I am not sure Cummins would like to be responsible for the rebirth of the TS3, 50 years after destroying it.

I would guess that Achates has done research and testing on a number of historically viable opposed-piston designs, to see how much they could be improved by applying current technology. Securing patents for these improvements, tested or not, can (assuming the ideas are sound) have the effect of controlling entry into the opposed-piston market. They may have even bought, or made a bid for, the OPOC patents last year.

cRiPpLe_rOoStEr 04-12-2018 11:37 PM


Originally Posted by acparker (Post 566608)
It was a (supposedly inferior) Cummins engine that replaced the TS3. Institutional prejudices can linger for decades. I am not sure Cummins would like to be responsible for the rebirth of the TS3, 50 years after destroying it.

Not sure if Cummins was really the one to blame for the phaseout of the TS3. IIRC it was Renault that did it, when it acquired the commercial vehicles operation of Rootes while Peugeot kept the car and LCV divisions.

acparker 04-13-2018 02:54 AM

It was actually Chrysler that purchased Rootes, beginning in 1967. They had just spent a sizeable amount of money developing a diesel engine with Cummins (who bought Perkins from Chrysler in 1964), so the first thing they did was shut down production of the TS3, destroyed most of the prototypes of the TS4, destroyed the drawings and disbanded the engine design team. They sold what was left of Rootes to Renault and Peugeot by 1978. Chrysler got its comeuppance during the Daimler-Benz merger.

acparker 05-03-2018 03:23 AM

For some excellent articles on opposed piston engines, I recommend reviewing this section at the Achates website (while it lasts):

Viewpoints - Achates

They also recommend this publication:

Opposed Piston Engines – Evolution, Use and Future Applications, by Martin Flint and Jean-Pierre Pirault.

cRiPpLe_rOoStEr 08-26-2020 06:57 PM

Opposed-piston engines are likely to make a comeback, now that Cummins is taking it seriously. I'm sure a civilian derivative of the ACE would easily find its way among the truck market.

acparker 08-26-2020 08:54 PM

Thanks for the information. I had been keeping an eye on Achates' progress, but not a close eye. It is about time one of these good ideas finally makes its way into production.

I still suspect there may be an advantage to the single-crankshaft design within a particular range of engine sizes.

I was going to mention earlier that perhaps at least some of the picturesque, orange wooden fishing boats at Mar del Plata in Argentina may still be powered by Rootes-Lister TS3 marine engines. I don't know if it would be worth the trip to go see them, but if you do, check if any are still around, and accessible, before you go.

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