Southdown Motor Services Ltd
1960
Commer Avenger IV
Harrington C35F
Southdown, ever primarily a Leyland operator (though Guy got a look in from time to time) also had a
modest requirement for lighter chassis. Despite having operated the OB model successfully, Southdown
then eschewed the Bedford SB when it looked for a lightweight coach chassis in the late 1950s. It is
understandable that the Bedford petrol engine did not appeal, and the alternative Perkins R6 was not a
very attractive diesel option either. From 1960 Bedford offered the SB with a Leyland engine, but even
this did not entice the Southdown company. Instead, whilst still favouring Leyland’s lightweight Tiger
Cub, hitherto highly conservative Southdown became surprisingly interested in the unconventional Tilling
Stevens TS3 opposed piston, three cylinder, horizontal two stroke engine, and bought 25 Beadle Rochester
C41F coaches in 1956-57. In 1959, after further Tiger Cub deliveries, Southdown returned to the TS3
engine with a batch of 15 Commer Avengers with Burlingham C35F bodies, their first from this
coachbuilder since the 1930s. Another batch of 15 Avengers followed in 1959-60, but these were given
Harrington Crusader Mk1 C35F bodies. The Beadles and the Commers all gave up to 12 years service with
Southdown, the last being sold off in 1971. I recall seeing - and hearing - the Avengers quite regularly
on the Brighton service along the A23. Their distinctive sound was unmistakeable. Seen here tucked away
in a corner of Victoria Coach Station in 1960 is the last of the Harrington batch, No.55, XUF 55.
Photograph and Copy contributed by Roger Cox
10/03/16 - 15:45
I hope the panelling and upholstery had sound deadening qualities of the
highest order. Detroit diesels of the period had a reputation for noise but the TS3 was in a league
of its own!
Phil Blinkhorn
11/03/16 - 05:56
A further batch followed 41-55 shown in Roger’s picture. There were 15,
numbered 56-70 (56-70 AUF) and were also bodied by Harrington. I assume that they were identical to
the earlier batch, but my memory of seeing them can no longer recall any detailed differences, if
any. I have just looked through the 2-volume history of Southdown by Colin Morris (Venture 1994),
and the Vol.2 fleet list only prints the Beadle-Commers 1-25, and has neither list or photo of the
Commer Avengers 26-70! Perhaps he had been deafened by the first 25?
Michael Hampton
11/03/16 - 05:56
It may be the angle of the photograph but this vehicle has a rather narrow
look about it. Were these coaches 7ft 6ins. or 8ft. wide?
Chris Barker
11/03/16 - 05:57
I’m not sure, Phil. I’ve been in a TS3-engined bus only twice: once in recent
years in a preserved coach at King Alfred Running Day at Winchester, and once fifty years ago
driving some folk from Reading to Portchester, Hants, in a coach belonging to Spiers of
Henley-on-Thames. As to the noise emanating from the exhaust pipe I agree with you all the way, but
inside the vehicles things seemed reasonably quiet. Perhaps I enjoyed the sound so much that I was
making undue allowances for it…
Commers raise a question in my mind: are they really a
lightweight in the same sense as a Bedford or a Ford is?
We often call the Leyland Tiger Cub a
lightweight, but I’d prefer a term like "three-quarterweight" or "quality
lightweight", since the feel of a Tiger Cub is solid and precise, like that of a heavyweight.
In the same way a Guy LUF is every bit as solid as the over-heavy UF.
On that basis perhaps
the Commer is a "five-eighths-weight".
Interested to hear fellow OBP-ers’
views.
Ian Thompson
11/03/16 - 12:05
I don’t recall seeing any of these at all - were they based in Portsmouth?
I’ve found a photo of one of each batch side-by-side and they look identical. SEE //tinyurl.com/z49qe6x
Chris Hebbron
11/03/16 - 15:26
That’s a fine image of the two examples from each batch standing together. The
only difference I can see is that the XUF driver’s mirrors are attached at the top of the
windscreen, whereas the AUF mirrors are attached at the bottom. (And of course the windscreen wipers
are facing in opposite directions…). My 1970 fleet list (SEC) shows the Portsmouth allocation
as 6 XUF + 3 AUF [9], Eastbourne 4 XUF + 3 AUF [7], Worthing 7 AUF, and Brighton 5 XUF + 2 AUF [7],
so they were quite well spread along the coast. The earlier Burlingham bodied batch (26-40) were at
Eastbourne (3), Brighton (6), and Chichester (6). This is likely to have been their final
allocations as Roger Cox notes that they had all gone by 1971, and the list I’m quoting from is
accurate to 1st November 1970.
Michael Hampton
12/03/16 - 05:47
There is one more minor difference between them and that is that the XUF’s
sported only a nearside spotlight; the AUF’s, one each side. Thanks, for the allocation details,
Michael. You’d have thought that Southdown would have kept them all at one depot for ease of
maintenance. Whilst I was looking for a photo of the other batch, I noticed photos of some of these
vehicles working for contractors, showing that some had a further life beyond Southdown.
Chris Hebbron
12/03/16 - 05:48
I think all of Southdown Commer coaches and all of the Commer-powered Beadle
coaches were eight foot wide. The reason that the Harrington-bodies look narrow is that they are
tall compared to similar bodies on Thames or Bedford chassis.
Stephen Allcroft
Roger Cox
Thanks, Michael for reminding me that there was a further batch of the
Harringtons. The straight framed Avenger was introduced in 1949, and the overall dimensions of the
109 bhp 4.75 litre six cylinder petrol engined Mk I were 27ft 6ins by 7ft 6ins. In 1952 the Mk II
increased the available dimensions to 30 ft by 8ft, but the petrol engine was retained. Then, in
1954, the Mk III appeared offering the TS3 engine as an option, and this became the Mk IV from 1956
when the petrol and smaller chassis alternatives were dropped. The standard rear axle ratio was 4.3
to 1, but the Eaton two speed axle was also offered. Taking up Ian’s point about internal noise, the
compact horizontal engine was installed over the front axle where the (no doubt well insulated)
floor went over it, and this contributed to the apparent height of the vehicle. The engine was thus
some way forward of the main saloon. Externally, of course, it was a different matter, and one could
hear TS3 powered coaches and lorries approaching when they were still leagues distant. The TS3
engine developed 105 bhp at 2400 rpm, but as with other large two strokes, the torque curve was very
peaky. Torque rose from 245 lb ft at 800 rpm to a maximum of 270 lb ft at 1200 rpm, but then fell
away sharply to 225 lb ft at the 2400 rpm governed speed. Theoretically, the 3.26 litre two stroke
TS3 equated to a four stroke motor of about 6.5 litres, though some efficiency and power losses
inherent in the type, notably the requirement for a Roots blower to aid induction and scavenging of
the cylinders, does prejudice a direct comparison. Nevertheless, as an illustration, the Gardner 5LW
of 6.974 litres yielded 300 lbs ft of torque across the entire working speed range. At 1700 rpm the
TS3 delivered only some 87 bhp against the 94 bhp of the Gardner. Even so, fuel consumption figures
of up to 20 mpg were claimed for the TS3. The standard gearbox in the Avenger Mk IV was a four speed
synchromesh unit, for which an optional overdrive was available, but a close ratio five speed
constant mesh box was also offered. I am not sure which of these the Southdown coaches had, though I
suspect the synchromesh. According to my records, the bare chassis weight of the Avenger was 3.125
tons, the maximum permissible gross weight being 9 tons. The maximum gross weight figure for the
contemporary Bedford SB was 8.26 tons. The unladen weight of a bodied contemporary Tiger Cub was
about 6 tons, which, with the full added weight for passengers, fuel, luggage etc, would raise this
to a maximum of around 9 tons. Perhaps, as Ian suggests, the Avenger was in a similar weight
category to the Tiger Cub rather than that of the lighter Bedford.
Roger Cox
13/03/16 - 14:54
Thx for the extra information, Roger. 20mpg was very good fuel consumption and
quite possible the prime reason, along with reliability, why this engine was so popular, when two
strokes were not highly regarded generally. I don’t know how general is the knowledge that Rootes
were well into developing a four-cylinder version of the engine, with several prototypes on the
bench. However, this was stymied by the Chrysler takeover and a clash with a similar effort between
Chrysler and Cummins. This resulted in a TSR2 scenario, with orders to scrap all traces of this
engine’s existence. Suffice to say that the Cummins engine was a complete failure and with the Plan
B TS4 scrapped, that was it. There are some stupid people about! The full story can be found here:
//tinyurl.com/gvjjutt
Chris Hebbron
14/03/16 - 06:52
I can confirm that my TS3 Rochester regularly achieves 18/20 mpg unless on a
hilly route.
My father was development driver for the TS4 and I believe there is a thread
somewhere on here about that engine
Roger Burdett
19/03/16 - 17:34
Roger Burdett’s actual consumption of 18-20 mpg for his TS3 Rochester is very
impressive. The power saved by having no valvegear to drive must be more than balanced by the energy
needed to drive the Roots blower, and all those extra large moving parts look as though they ought
to sap power, but evidently not. Since simple crankcase-scavenge 2-stroke engines—whether
petrol or diesel—always show poor fuel consumption, it’s easy to assume that all 2-strokes are
thirsty by nature, yet the most economical prime mover ever built was the Wärtsilä-Sulzer RT-flex
96C 2-stroke marine engine, which is well worth Googling, until it was recently just overtaken by a
4-stroke engine (model 31) by the same Finnish builder. Both these engines are admittedly a trifle
bulky for a coach, but they show what’s possible.
Roger, how does the consumption of your
rear-engined Foden coach compare with that of other vehicles of a similar weight?
Ian Thompson
21/03/16 - 09:00
Ian my Foden consumption is around 12mpg but is inherently more unreliable
than the Commer. The fuel system is more complex with a hydraulic governor and to be honest has not
had the use it deserved. My LS Gardner powered which is comparable weight is c13.5mpg. The Leylands
do around 12 and the Midland Reds 10.
As a rule all my Gardners do 13-14mpg whether 5LW; 6LW,
or 6HLX except for my Tilling Stevens which with an overdrive 6LW does 17/18. The Commer is 3.1
litre with no overdrive but is incredibly fuel efficient as you say with the direct injection and a
fairly low vehicle weight. The Roots blower once it is moving has far fewer parts than a a vehicle
with valve gear. I do run the vehicle between 55-65mph on the motorway which always surprises speed
limited modern coaches!
Roger Burdett
14/09/16 - 14:05
Here is a picture of my TS3 Avenger IV The Commer stands at 11 foot high so
does look narrow but it is in fact the height that creates the illusion.
Yes 20 mpg is
returnable without difficulty, as is cruising at 60 mph.
Russell Price
15/09/16 - 06:46
Those consumption figures for the TS3 engine underline the utter folly of
Chrysler in abandoning the promising TS4 development. That engine would have surely been a winner,
giving up to 200 bhp and 465 lb ft torque at 1800 rpm, all from 4.7 litres. The TS3 also proved to
be outstandingly reliable, the weakest part apparently being the drive to the Roots blower. In
playing the American card and going for V6/V8 from Cummins, Chrysler bought possibly the worst
engine lemons ever to go into volume production. It’s a miracle that Cummins survived that debacle.
On that note, there is a picture on the following site of a Black & White Daimler Roadliner fitted
with a TS3 engine:- www.flickr.com/photos/
I gather that it
performed quite satisfactorily, and I wonder why others didn’t try this conversion. Today large two
stroke engines fall foul of emission regulations, but the TS4 could have had its heyday well before
those rules came into force.
Roger Cox
16/09/16 - 06:24
My father was test driver at Rootes for the TS4 and noise would have killed it
as the harmonics were much greater than the Cummins. Let us not forget Cummins was part of Chrysler
at that time and the V6/V8 production was only a small part of a big world wide conglomerate.
My father drove the V8 everyday in lorry form and units used to go Coventry-Linwood return 6
days per week up days back nights (different driver). That was 3500 miles per week. Reliability was
an issue but never as great as in the Buses or the AEC V8 in the lorries
Roger Burdett
16/09/16 - 06:24
I believe it was noise regulations of 1972/3 that finally killed off the TS3
and TS4. I would agree in 30 odd years of owning it is a well engineered reliable machine.
Russell Price
16/09/16 - 13:35
I was working for Chrysler in Truck development at the time of the TS4. As we
understood it, the TS4 greatly outperformed the Cummins V6/V8 in all aspects, but Cummins (a major
part of Chrysler at the time) had invested a lot of cash in the V6/V8 and they did not intend to
lose it! All the tooling for the TS4 had been ordered & delivered to the Whitley plant in Coventry,
where it was put into store and eventually sold for scrap…brand new & unused. It was said at
the time that caused the collapse and subsequent closure of Herbert Machine Tools. Cummins "Red
Engines" had a number of unusual design feature. They were high speed diesels, which was a
problem since drivers were not used to revving a diesel to get performance. In fact a special rev
counter was fitted to the trucks with a green band (gear shifting range) and a blue band, complete
with a sticker that read "Always drive in the blue band". All fuel lines were drilled into
the block, so it was a "clean" engine on the outside, but a problem if you got a blocked
fuel line. Originally fitted with rocker operated 3 hole injectors, they suffered a bit of fuel
starvation. This was overcome by changing to 5 hole injectors, which were slightly taller than the 3
hole and so necessitated changing the push rods, otherwise, bent push rods and a very unhappy
engine! How do we know this? Let’s just say put it down to personal experience and move on!! The V8
was 185hp and the V6 was 160 hp. I think the only production Dodge that had the V6 was the L600, low
height chassis, whereas Guy Motors took the V6 for a full size truck (Guy Warrior I think). The
failure rate on the Red Engines was huge and we had a large pile of dead engines in the Whitley
compound (Chrysler truck development relocated to Coventry from Luton & Dunstable at the end of the
1960’s). I hope this is of interest to you.
David Field
16/09/16 - 17:09
Thanks to David Field for the latest comments. The engine Guy used in the Big
J was the VIM v-6 & Vine v-8. These were going to be built in the UK at the former Henry Meadows
factory in a joint venture with Jaguar which did not go through. To bring things back to buses it
was the Cummins VIM v-6 of 9.6 litres and 192bhp that was launched in the Daimler Roadliner.
Stephen Allcroft
17/09/16 - 05:11
A further bit of trivia regarding the TS3. Lord Rootes was a man who was not
renowned for great judgement or making the best decisions. For example, after WW2 he was offered a
choice of German engineering businesses as reparation for the damage done to Rootes group factories
in UK. His options were VW car manufacturing or a rather strange and obscure 2 stroke engine being
developed for aeroplanes (Heinkel I think). He chose the latter, apparently on the basis that the VW
would never prove to be popular!
Does anyone know if TS3 engine PSV’s used the Maxiload oil
bath air cleaner (located under the passenger seat on the truck) and the Cooper’s self cleaning
muffler? Why I ask is because when the TS3 was stretched to 135hp in it’s final form (a stretch too
far) one of the problems was that the blower shaft would snap. The first sign of this was a drop in
power and the second sign was black oily smoke pouring out through the air filter - not good in a
PSV. The quick way of replacing the shaft was to remove the radiator to get to the front of the
engine. The front part of the broken shaft was easy to get at, but the rear part involved careful
use of a couple of welding rods fused together and poked down the hole. The idea was that you would
strike an arc onto the steel shaft and not the alloy block! I was wondering how you get to the front
of the engine in both the Harrington and Plaxton bodies featured.
The Coopers muffler would
probably scare passengers and other road users half to death today. Carbon was allowed to build up
in the muffler until a certain back pressure and exhaust gas temperature was reached. There was then
a discernible loud pop as the carbon ignited and was sent out through the tail pipe, as a trail of
sparks and sometimes even the odd flame. Very impressive at night on the motorway!
David Field
17/09/16 - 11:41
The posts about the fascinating TS3/4 have been very interesting. Your point,
David F, about the Coopers muffler spewing forth sparks reminds me of being in a express steam
train, in the mid-1950’s, spewing out glowing smuts whilst climbing Shap Fell flat out at night. It
was like descending into Dante’s Inferno! Not a time to put one’s head out of the window!
Chris Hebbron
17/09/16 - 18:36
Hmm yes the standard air filter on an Avenger IV is indeed right under the
front double seat alongside the driver! It is essential to use silencers on a TS3 with the correct
amount of back pressure. I have on several occasions had flames out of the exhaust of UN mainly when
running well last time was on the A419 Swindon Cirencester section. The access to the engine is
absolutely dire!! wont say more
Russell Price
07/08/17 - 06:41
Having had only fleeting experience of the Commer marque in my early days at
SMS - 45 and 60 I think being the two we had at our depot - I really can’t think of a good word to
say about them. The potential brake fade and a sound like an Atco powered football rattle were
enough to put me off for life.
However, from before my time, am I right in thinking that the
first batch (pre-Harrington) were the notorious ones that eventually ended up derelict in Bognor
Yard with brambles etc growing through them? There was a story that the design didn’t allow for the
removal of the engine which was an integral requirement in an ‘E Dock’, and they were
consigned to Bognor as that maintenance time came. Thereafter, anyone saying ‘Bognor Yard’
about something was immediately understood as meaning ‘throw it away’.
Nick Turner
