Rare Beasts: Guy underfloors in Australia

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RK215
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Post by RK215 »

That’s certainly an interesting gearchange gate layout, particularly the backward dogleg to reverse (well, I assume its reverse).

I have a 1956 brochure for the Guy Arab IV (single-deck version) that describes the preselector gearshift as follows:

“Normal “H” type gate change provided, travel from the neutral position to engage each gear being equidistant.”

Unfortunately, it is not illustrated, but from the description, it is not the same as that shown above.

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hij
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Post by hij »

Cheers Herb, I did belatedly see that pic not long after I posted the request. What exactly is the gear situation here, simply 1, 2, 3 & as stated by RK215 reverse? I'm completely ignorant of most of these old gals.
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Herbert
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Post by Herbert »

Yes, R is the dog-leg from 2nd. When moving the selector to 3rd & 4th, the alignment of the lever to the gearbox remains in one plane. The lever in the gate moves sideways on a spring. Therefore, the gears positions are really in a straight line. You could select 3rd & 4th from the first row of the gate if you put it in the right position. So in effect, in order the gears are 1, 3, N, 4, 2, R.

It is interesting to note that the alignment of gears is different on AEC pre-selects with the column-mounted selector. On these, as you move the lever from neutral, you need to press down against the spring to use the lower gate. Moving the lever down, then forward, the first position is 3rd, further forward is 1st, and by lifting a catch, you reach R. Going the other way on the lower gate, there's only one positon, 2nd. Using the upper slot, moving from neutral only has one forward position, 3rd, but moving the lever backwards the first position is 2nd, then further back is 4th. The gears are also, therefore, in one plane, but the order is different: R, 1, 3, N, 2, 4.

Image

This demonstrates that there were differences to the Wilson gearbox depending on who manufactured it.
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hij
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Post by hij »

Thanks, that's interesting. It's been a long time since I've driven a gear-select, and that was a semi-auto panther.
Any other pics and configs?
What about that guy arab you were seen "haulin' A" away from Whiteman pk in not long ago?
RK215
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Post by RK215 »

Nice pic of the AEC preselector gearshift, thanks Herbert! It shows how the head and shaft were a bit skewed relative to the steering column.

On quadrant patterns, the Auckland Daimler Freelines were different again, with a right hand lever, and – if I remember this correctly - the gears being R, 1, 3, N, 4, 2 from front to back. 3 and 4 were in the shorter upper leg of the H, R, 1 and 2 being on the longer lower leg. The reverse interlock button was of the lift-up type.

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Post by Herbert »

As I only ever had one ride on a 5sp Freeline, I cannot recall where or how long the slot was for 1st gear - but I do remember 1st being used on that trip (the bus was a participant in a Perth bus rally in the early 1980s; sadly soon after this bus was destroyed in an accident). As 1st was a "bog" gear, 2nd-5th were in the positions where 1st-4th were on a 4sp box.
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Post by RK215 »

Information on the Guy Arab UF is scant. However, it had what was probably the most complex chassis design of the early British underfloor models, none of which were as simple as the later models with their standard-width (34 inches) essentially straight frames. The Arab UF frame, as well as being arched over the rear axle, had a raised section above the engine, thus presaging the layout later seen on the Volvo B58 and B10M. Its speculation on my part, but I wonder if Guy had used the Sunbeam MF2B trolleybus chassis as a starting point in its development of the Arab UF?

Guy also developed a light weight version, the Arab LUF, which retained the same chassis style as the Arab UF, in contrast to AEC and Leyland, who adopted straight frames for the Reliance and Tiger Cub. The Arab LUF seems to have been available in short wheelbase form (16’4”) only, whereas the Arab UF came in 16’4” and 17’6” versions. The LUF could have vacuum or air brakes; in the later case of the triple servo form, analogous to the standard vacuum layout, but quite rare.

Guy built both spring- and air-operated preselector gearboxes in 4-speed, 5-speed low 1st and 5-speed overdrive versions. I have seen the air-operated type described as “air assisted”. However, a look through the Guy literature on hand shows a picture of what looks to be an internally an air-operated unit, with an AEC-like pentagonal top plate over the air cylinder, from which emerges an air line connection. So the conclusion is that it was air-operated, not air assisted. I cannot find any information as to how Guy’s “equidistant-from-neutral” gear selector mechanism worked. Perhaps it was arranged so that, in the 4-speed case, movement of the gearstick in the 1st-2nd plane produced greater fore-and-aft movement of the selector rod back to the gearbox than the same gearstick movement in the 3rd-4th plane.

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Herbert
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Post by Herbert »

RK215 wrote:I cannot find any information as to how Guy’s “equidistant-from-neutral” gear selector mechanism worked. Perhaps it was arranged so that, in the 4-speed case, movement of the gearstick in the 1st-2nd plane produced greater fore-and-aft movement of the selector rod back to the gearbox than the same gearstick movement in the 3rd-4th plane.
From the gate arrangement on the WAGT Guys, that would seem likely - and it makes sense, too, as the majority of gear changes would likely to be between 3rd & 4th. Also, it was standard practice (ala London Transport) to pre-select 3rd once you were in top gear (obviously not in LT Guys as they were wartime utility crash boxes!).

I only ever saw 308 (ie Perth's sole Guy underfloor) "in the flesh" once, and cannot remember the movement of its selector, however it did retain the original Guy gear lever. Being an odd-ball, it used to be permanently allocated to the same (and apparently very grumpy) Causeway driver. Dennis96 will know more as he travelled on it.

These threads are really interesting - and bring to mind other Perth odd-balls that you might be interested in, eg rear-engined Fodens, underfloor-engined Dennis Lancet LU2. I'd also like to pick your brain over post-war Dennis Lancet model numbers, if you've got that sort of info.
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Post by RK215 »

Herbert wrote:These threads are really interesting - and bring to mind other Perth odd-balls that you might be interested in, eg rear-engined Fodens, underfloor-engined Dennis Lancet LU2. I'd also like to pick your brain over post-war Dennis Lancet model numbers, if you've got that sort of info.
Sorry, Herbert, nothing in the memory bank on the Dennis Lancet, but I'll check to see what I have and post accordingly. I once did see a rear-engined Foden - with the 2-stroke engine - from a distance in Napier, it being ex-Whenuapai Bus Co, West Auckland, where we arrived just after they had gone. I did get to regularly ride in other WBC "delights", though, such as utility Ford V8s, with totally undamped front suspension, retrofitted with Thames 4D engines, deep 1st gearboxes and two-speed axles. Much fun was the pull away from the Albert St city stop in 2nd low, up to 2nd high for a foot-hard-down right-turn into Wellesley Street on a stale green light, front axle skipping sideways, then screaming at 3000 rev/min (tachometer conveniently mounted on the engine cover for observation from the front right-hand passenger seat that no-one else wanted anyway) on the short climb up to Hobson Street. These days, 40+ years on, I prefer quiet buses, some days even the hub-reduction groan on the Sydney Mercs and MANs is annoying.

It is becoming apparent it seems that Perth had an eclectic collection of buses, including some delightful rarities.

Mention of the Foden brings to mind the diversity of diesel engine designs that abounded back in the 1950s. The Foden FD and Commer TS3 were both "maverick" designs by UK standards, the Commer particularly so, being a single-crankshaft opposed piston design. Not road transport engines, but other "unusual" opposed piston designs from the UK were the Napier Deltic and Doxford. For sheer complexity, the Napier Nomad turbo-compound aircraft diesel would be hard to beat. And I guess we shouldn't overlook the Crossley pulse-scavenged two-stroke as used in the WAGR X class diesel-electric locomotives. That one - and the locomotive itself - is surely a case of "what were they thinking?".

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Dennis96
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Odd Ball uses in Perth and New Zealand DF Class Locomotives

Post by Dennis96 »

007 raises some interesting points. Perth's solitary Guy Arab underfloor bus - WA Government Tramways 135 renumbered into the MTT fleet as 308 always seemed gutless to me when compared with a Guy Arab III half cab. Both of which had Gardner 6LW engines - the engine in 308 being a 6HLW. But then 308 was the first of 21 buses with the same body, - the other 20 being Daimler Freelines with Daimler engines. Now the Daimlers really had some get up and go, when compared with any contemporary bus powered by Leyland or AEC, so perhaps my memories of 135 aka 308 are clouded.

In its latter days 308 did the same run every afternoon and had the same driver. There were several theories about this chap. Firstly, he was knocking off a lady that lived near the route 32 terminus in Como. (I got some great shots of Guy Arab half cab 333 laying over at the terminus when he was "doing his thing" when 308 was unavailable for repairs or a service). The second theory was that he was a piss tank and the only reason he never got the sack was because he was in the same lodge as the General Manager of the MTT.

On another front and as 'Erbie 'as raised it, what can any of our New Zealand correspondents tell me about the New Zealand Railways Df class English Electric locomotives that had a 2-Co-Co-2 wheel arrangement. How successful/reliable were they?
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RK215
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Re: Odd Ball uses in Perth and New Zealand DF Class Locomoti

Post by RK215 »

Dennis96 wrote:On another front and as 'Erbie 'as raised it, what can any of our New Zealand correspondents tell me about the New Zealand Railways Df class English Electric locomotives that had a 2-Co-Co-2 wheel arrangement. How successful/reliable were they?
They had a bad reputation and a relatively short life, although to some extent it was a case of "give a dog a bad name". In their waning years they were thrashed to death on the Bay of Plenty line, as were the 5 members of the EE Rocklea Di class, which worked alongside them in that period. Analysis suggests that the "problems" were in part due to the fact that English Electric was still on a learning curve, particularly with the Mark II vee engine; in this aspect the NZR experience would have been similar to hat of QR with the 1200 class. Certain aspects of their design, such as the constricted height and width, made maintenance access difficult, which didn't help. And they were orphans in the NZR fleet.

But with their bad reputation and short life, they were "outliers" in the EE export world of the 1950s. The Rhodesian DE2 class 1-Co-Co-1, first built in 1955, was very highly regarded and some lasted above 40 years. And I heard it from a KTM Malaysia engineer a couple or so years back that the 20 class EE's, built from 1957, were its best-ever locomotives. I haven't yet heard how KTM's new Dalian locomotives with Ruston 16RK215 engines are doing. But CGR Sri Lanka seemed to be happy enough with its 12RK215-powered Alsthoms, which sound a bit like a Df. (They are much neater inside, though - haven't been inside a Df so I'm using the Dg as a yardstick here.)

The 10 Df's were the only diesel locomotives to use the 2-Co-Co-2 wheel arrangement; the only others of any kind were the 1938 pair of GE steam turbine electric prototypes that were tried by the UP. There were around 500 electric locomotives with the 2-Co+Co-2 wheel arrangement, which although apparently similar, was quite different in its dynamic behaviour. JNR had the lion's share, with its last version, the EF58 class, built as late as 1958. Interestingly, the first electric locomotives with the 2-Co+Co-2 wheel arrangement were built by EE for the Japan Government circa 1925, becoming the JNR EF50 class.

More to follow on the Df when I get a chance, unless it's off-topic, although it can be done as part of the EE 12-cylinder model evolution story, in which the Rocklea models are fairly central.

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Post by RK215 »

Herbert wrote:[These threads are really interesting - and bring to mind other Perth odd-balls that you might be interested in, eg rear-engined Fodens, underfloor-engined Dennis Lancet LU2. I'd also like to pick your brain over post-war Dennis Lancet model numbers, if you've got that sort of info.
No luck with Lancet UF model numbers, I’m afraid, but I’ll keep the item in mind.

Very few Lancet UF’s were built, less than 100 I think. It was a little unusual, with a drop-front chassis, Lockheed constant-flow hydraulic brakes and an odd gearbox, basically a sliding-mesh (i.e. true “crash”) 4-speed design with a 5th, constant-mesh overdrive gear that was preselected. (The same idea of a preselected overdrive 5th crops up somewhere else in British bus history, but right now I can’t remember where.)

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Dennis96
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Dennis Lancer UF and English Electric

Post by Dennis96 »

The Dennis Lancet UF had the same 5 speed gearbox with pre-select overdrive fifth gear as the J3 and J3A models.

I'd like to further explore English Electric's diesel locos further with RK 215, maybe off line if more appropriate. Reason being that I am researching the 48 Metropolitan-Vickers built X class 2-Do-2 diesel electric locomotives of the Western Australian Government Railways (WAGR) and am anxious to find out what English Electric may have offered the WAGR. Files with details of tenders received have been destroyed, but given the WAGR's insistence on 1100 horsepower and a 10 ton axle load, one speculates EE may have offered a 2-Co-Co-2 wheel arrangement.
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RK215
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Post by RK215 »

I had started writing a few notes on the NZR Df and the QR 1200, which I may as well post anyway, but the WAGR case puts the subject in a new perspective.

I have come across very little information on EE designs that were offered as part of unsuccessful bids. One of the few snippets that I have is that evidently the NZR Dg was an adaptation of a design offered to QR, presumably against the requirement that led to the 1170 class. EE also offered a 6-cylinder model against the CR tender that led to the NSU class; I imagine that it was similar to that offered to QR, and may even be the original in this “series”.

The WAGR 1100 hp requirement would have posed a problem to EE. The 8-cylinder engine went to 1000 hp in early Mark II form, the 1100 hp rating not being available until circa 1960. Some site derating would have been necessary, as well. So to avoid coming up short on power, it would need to have used the 12-cylinder engine, which would then have created a weight problem. Interestingly, early sketches for the Df suggested a total weight of 84 tons, and an adhesive weight of 60 tons, which would have matched the WAGR 10 ton axle loading. But as the weight comparisons in my nest posting will show, 84 tons total was surely wishful thinking. The lightest EE “twelve”, the 1969 Ghana 1851 class Co-Co, came in at 82 tons. Later on, EE became quite adept at building light but conventional locomotive structures, as evidenced by the DP2 prototype. However, that postdates the era we are talking of. Perhaps, though, if 84/60 tons was the best estimate for the 2-Co-Co-2 design at the time of the WAGR tender, it was submitted as such. Whilst the WAGR X, CR NSU, QR 1200 and NZR Df all stemmed from inquiries/initial thoughts circa 1950, there may have been some differences in the timings of contract placements.

60 tons adhesive and say 8 tons on each pilot truck axle would have allowed a total weight of 92 tons, probably still not enough margin to accommodate the 12SVT engine at the early 1950s state of the art. Speculatively looking at other possibilities that EE may have considered, the 8SRKT engine probably could have been gotten on to a 1-Co-Co-1 at around 86 tons total. EE must have had this wheel arrangement in mind quite early on, bearing in mind that the Rhodesian DE2 order was placed in 1952. Whilst it seems unlikely given its interest in good bogie design, EE might also have considered repeating the 1A-Do-A1 rigid-frame arrangement, used on the Egyptian 3000 series, at least for an 8-cylinder option.

None of the WAGR X information I have seen provides a full rationale for its anachronistic 2-Do-2 wheel arrangement. Clearly, the specification demanded something unusual. And Metrovick was not averse to using 1930’s ideas, witness the articulated bogie (Co+Co) NSWGR class 46 DC electric. Also, Beyer Peacock may have been more comfortable with a steam-age concept. In some ways it seemed to be fairly well anchored in the past, for example still using plate frames and underslung springs for otherwise reasonably modern steam locomotives. It is on record as being against cast frames for larger steam locomotives, although the relative performance of the SAR GMAM as compared with the RR 20 pretty well demolished its position. So perhaps the X was the product of two builders with rather large rearview mirrors, and an engine builder whom I think was competing with North British for the most hapless and hopeless award in the diesel stakes. I wonder, though, whether WAGR was also influential. Somewhere – not to hand right now – I have some Railway Gazette articles by Clarke of WAGR about track stress. If I remember rightly, the data presented suggests that the X may have produced lower vertical railhead stresses than the QR 1170 and perhaps the CR NSU. Even were that the case, the lateral railhead stress was probably higher for the X. I guess the question here is, why a 2-Do-2 and not, say a 1-Co-Co-1 or a 2-Bo-Bo-2. Both would have been kinder to the track, and the 1-Co-Co-1 would have had higher adhesion weight, probably usefully so.

Digressing a little into interesting “connections”, the Metrovick 10-notch control system used on the X (and on the CIE A and C classes) was evidently derived from Sulzer practice, with whom Metrovick worked on the pair of CIE prototypes. Sulzer was quite particular about the control systems used with its engines, and right after WWII moved from BBC precepts to its own 10-notch system, although always acknowledging the pioneering work of Lemp. When BR wanted a common, electropneumatic control and MU system for all its pilot plan diesel-electrics, Metrovick resisted and the result was that BR accepted a second, electromagnetic system, also used by Brush and GEC. Meanwhile, in the early 1950s, Sulzer had moved on to a hybrid system, basically electropneumatic, but with electromagnetic starting notches. The CR NSU was an early example of a Sulzer-engined locomotive so-fitted. Exactly why EE developed its own electropneumatic control system, first used in 1954, is not recorded. But it is known that BR was not too happy with the 8-notch control system fitted to prototypes 10000/1 and 10201/2. And EE must have known that the BR engineers were very favourably disposed to Sulzer. So there is strong circumstantial evidence of Sulzer influence. EE’s electropneumatic control system did not require electric starting notches, but as adopted by BR, provision was made for their optional use, one imagines to accommodate Sulzer. However, none of the pilot plan Sulzers actually used them. The EE electropneumatic control system was used on most Rocklea-built locomotives. As with the Leyland group buses, “downunder” was very much intertwined with the development pathways.

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Post by RK215 »

RK215 wrote:I had started writing a few notes on the NZR Df and the QR 1200, which I may as well post anyway, ...
The following was written before the previous post, but laziness has got in the way of editing for seamless continuity.

NZR ordered the Df at about the same time that QR ordered its 1200 class, but the Df’s were delivered about a year later. Both were delayed, mostly due to the UK steel shortage of the time. The additional delay to the Df was allegedly due to the difficulties in finalizing the design.

The designs shared the same engine (12SVT II), main generator (EE828) and traction motors (EE525), and the control systems were similar. The gearing was slightly different, 61:15 for the Df and 65:15 for the 1200. The 1200 was also derated for Queensland site conditions. It turned out to be both the first use of the EE V12 engine, and the first use of the Mark II version of the EE RK/V engine.

But whereas the 1200 was a relatively straightforward design in a mechanical sense, albeit with a quirk or two, the Df was complex. NZR had set an ambitious set of targets for its first mainline diesel-electric design. It wanted a locomotive with the same haulage capacity (at least at freight train speeds) as its K/Ka class 4-8-4 steam locomotives, but with the same high route availability as its lighter J/Ja class 4-8-2 steam locomotives, this implying a relatively low axle loading. At the time, low-frequency AC electrification of the North Island Main Trunk (NIMT) was planned. Thus any diesels bought for interim use on the NIMT would need to be redeployable on the lighter-track provincial lines post-electrification. In the event, the original electrification proposal didn’t proceed, but the Df’s were displaced from the NIMT by the Da class (EMD G12).

Additional to the low axle loading (12 tons), NZR also wanted additional diesel benefits, including dynamic braking, full bidirectional operation (i.e. two cabs), and provision for one-man operation. The last-mentioned was never realized, but designing for it left the legacy of a rather cramped cab, although meeting the weight target may also have been a contributing factor.

All of this had to fit into the then-applicable rather tight NZR loading gauge, which allowed a maximum width of 8’6” and a maximum height of 11’6”. As the EE V12 engine was 5’6” wide, there was not much room either side of it in the carbody.

It was evident that an unusual wheel arrangement would be required. The QR 1200, a conventional Co-Co, came in at 90 tons, with a 15 ton axle loading. The later KTM 20 class, to a first approximation a double-cabbed 1200, came in at 96 tons. Add dynamic braking equipment, and the total weight was clearly going to be beyond what could be carried on 8 axles at 12 tons each, not taking account of the extra weight added by more complex running gear. So really, the designers had nowhere to go but ten axles and 2-Co-Co-2, for a total weight of 108 tons. EE designed what was reputedly very good running gear from both the riding and tracking viewpoint. The bogies were a mix of bar frames and castings, bearing some resemblance to those on the JNR EF58 class DC electric locomotives. With this kind of wheel arrangement, it is possible to arrange axle spacings to provide rail bending moment relief, according to the same principle that saw tapered axle loadings used on the CR NT class. In fact, and probably for this reason, the Df class had wider route availability than the Dg class, which had an 11½ ton axle loading.

The Df was something of a starting point for EE with this kind of carefully-spaced, tapered axle loading running gear. Next was the 1955 Rhodesian DE2 class, with 1-Co-Co-1 running gear, in this case with a cast main bogie, supplied by Henricot of Belgium, predecessor of several pilot truck designs for African railways, all noted for their kindness to the track. From this group must be excluded the British Rail class 40, though, which EE built as a 1-Co-Co-1 only under duress. It proposed a Co-Co, but BR was concerned that it might not meet the weight targets, and its civil engineers preferred a pilot truck for sustained high-speed running. Perhaps, though, BR’s real reason for insisting on 1-Co-Co-1 was that its home-built, Sulzer-engined class 44 Type 4 “flagship” definitely needed more than 6 axles, and BR certainly didn’t want to be upstaged by EE. Furthermore, BR was going to use the existing terribly awful (no, worse than that) Bulleid/Bolland plate-frame 1-Co bogie designed for SR prototypes 10201/2/3, so naturally insisted that EE do the same. The BR workshops could easily handle plate frames, but bar frames would have been a struggle. And buying-in a cast bogie from an outside supplier was probably precluded both by the labour politics of the era, and cost, The EE engineers must have choked on all of this. Why build a 1-Co-Co-1 when a simple Co-Co would be just fine, and if a 1-Co-Co-1 was really necessary, surely the DE2 bogie design showed the way.

Anyway, back to the main theme, the early EE Mark II engines were not fully developed. Tufnell, who was with EE in the period at interest, has recorded in his writings that EE only half did the upgrade job in going from the Mark I to the Mark II. Early changes required to allow sustained operation at the top rotational speed of 850 rev/min were dynamically balanced crankshafts and inclined-bolt connecting rods, which were applied as retrofits. I think that NZR may have suffered more than QR, perhaps because its engines were not derated. The difficulties of working on the engine in the narrow carbody couldn’t have helped, either. But that said, the carbodies of the KTM 20 and BR 37 were only incrementally wider, and the 37 fleet has had a very long life.

EE was slow in applying the upgrades to production engines, apparently because it wanted to use up existing parts stocks before adopting new patterns. This may have been a combination of parsimony and practice necessitated during the steel shortage.

As said, the QR 1200 had a quirk or two. To start with, it was a non-MU equipped single-ended cab unit, which right away limited its utility. Although in context, QR did not adopt MU for its mainline diesel locomotives until 1960. The bogies were of the riveted type. At the time, EE was no stranger to either cast or bar frame bogies. So it is at least possible that the choice of a fabricated design on the 1200, and also on the contemporaneous VR L class electric, relates to the UK steel shortage, in which users were encouraged to make maximum use of standard plates, etc., rather than special forms. A basically similar fabricated bogie design was used on the 1954 8-cylinder locomotives that EE supplied to Nordeste, Brasil. Some changes were made on similar locomotives supplied Buenos Aires Provincial in 1956, and the final iteration of this design, supplied to Belgrano, Argentina in 1959, had a welded version with underslung equalizers, not unlike the bogies fitted to the MRWA F class, bringing this digression back to Australia. Another unusual feature of the 1200 was that the bogies were quite widely spaced in relationship to the overall length. This can be seen by comparing it with the later 1250, 1270 and 1300 classes. The final QR 12-cylinder EE type, the 2350, went the other way, with relatively short bogie spacing. I have read somewhere that for its early mainline diesels, QR wanted to approximate Garratt bridge loading, albeit on 6 rather than 8 driving axles, and that this explained the bogie spacing.

(to be continued)
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Post by Rick R »

Herbert wrote:
Image
The pre-war AEC pre-pesectors had a floor mounted gear lever which travelled via an identical pattern as shown above (lift to get from 1 to R). To tell a pre-selector from a crashbox, the crashbox types had a ball shaped knob on the end of the sitck, whilst the pre-selectors had a mushroom shaped knob.
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Post by Herbert »

Interesting that you posted those comments about the different knobs on pre-select & crash box gear levers, Rick - I've just left a similar note on the thread about the Canberra Regal!

Thanks for the additional information about the "H" pattern of the earlier pre-selectors - something I didn't know for sure since I'd never seen one. I've read that the actuator pedal on an AEC mechanical pre-select assumed a different position for each gear, and remained down when in neutral. Does anyone know whether this was only on AECs, or did Daimler mechanical pre-selectors do the same?
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Post by TX »

Adelaide AEC Regal IV 623, at the St. Kilda museum, has a wooden knob on its preselector. Not sure if the Adelaide buses originally had wood preselector knobs. Here are a couple of pictures of bus 623's gear lever:

Image Image
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Post by Herbert »

Thanks TX.

Here's a couple of views of preserved Kalamunda 17 (became MTT 201) for comparison.

Image
Image

Kalamunda 17 is about 4 years older than Adelaide MTT 623. Incidentally, it was the first underfloor engined bus in Perth.
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Post by RK215 »

Herbert wrote: I've read that the actuator pedal on an AEC mechanical pre-select assumed a different position for each gear, and remained down when in neutral. Does anyone know whether this was only on AECs, or did Daimler mechanical pre-selectors do the same?
I don’t know the answer to this question.

For the AEC gearchange pedal to behave as described, it seems that it would have to have been coupled to the gearbox busbar without any overrunning device. In neutral, the busbar is held in the down position, so correspondingly the pedal would also be down, although with enough movement left to push the busbar down a little more to allow the struts to clear. In each gear, it’s conceivable that slight variations in strut displacement could result in slightly different pedal positions.

On the other hand, a simple overrunning device would ensure that, whilst the busbar followed the pedal depression, the pedal could return (through its own return spring) even when the busbar stayed down. I don’t know, but I would guess that the Daimler and Guy post-WWII mechanically operated preselector gearboxes were like this. In particular, Guy built both spring- and air-operated types side-by-side from the start; it seems unlikely that it would have opted for differing pedal behaviours.

Anyway, it’s another interesting facet of epicyclic gearbox evolution to be further investigated!

And talking of differences, something I noticed recently from looking closely at brochure illustrations is that the Daimler air operated preselector (introduced in 1956 for the CVD/G6-30 double-deck model) had its quadrant gear (which drives the camshaft skew gear) upside down as compared with the AEC and Guy pattern.

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Post by RK215 »

Getting back to the Guy Arab UF, one might ask why did WAGT buy only the single example?

Perhaps it anticipated that such a bus with the Gardner 6HLW engine would be underpowered for its duties, but being an established Guy customer, bought one just to confirm its theory, and to "show willing" to at least try. WAGT chose the Daimler 650 (10.6 litre) engine rather than the 6HLW for its concurrent Freeline fleet, which points to a preference for adequate power over reliability and durability. The Daimler 650 engine was certainly quite smooth and gave the Freeline a performance edge over contemporary underfloors, even the Worldmaster, but it was not a strong unit, and had a tendency to crack cylinder heads and blocks.

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Post by Herbert »

The reliability issue with the Daimler engine seems to be reflected in the large numbers of Freelines that were sacrificed so that their sisters could be kept running (9 out of 31). Similarly, the number of CVD6s scrapped for parts (4 out of 9). Much lower stats for the Gardners.

As to why only one Guy UF, one could also ask why not Regal IVs considering the WAGT had two batches of Regal IIIs. Would be wonderful if Guy_Arab has further info on these questions.
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RK215
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Post by RK215 »

Good point.

A 9.6-engined Regal IV was a ponderous beast, too, although one would expect it to be a little more sprightly than an Arab UF.

Regarding WAGT's liking for Daimlers, from the Daimler literature of the period one can deduce that the Perth office was its primary Australian operation. So just perhaps Daimler was able to make a stronger sales and support case in WA than in other states.

I don't have the comparable information for Guy. But it's curious that it too did well in WA as compared with other states.

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Post by hij »

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Dennis96
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Daimler D650HS versus the rest ...

Post by Dennis96 »

With 160 bhp under the floor, the Daimler Freelines were a lot more sprightly than the AEC Regal IV and Leyland Worldmasters of the day. The Gardner 6LW on the solitary Guy Arab underfloor only put oput 102 bhp and this really showed in its sluggishness.

The Daimler engines were no more, nor no less reliable than their AEC and Leyland counterparts, which is evidenced by the fact some of these buses lasted 25 years in revenue service. It was more the unavailability and cost of parts that caused the MTT to look at earlier withdrawals of some of the Freelines whose bodies were coming due for major work. Remeber, Jaguar Cars took over Daimler in the early 1960's and subsequently became part of British Leyland. It is uderstandable that supplies of specialised Daimler engine parts would dry up prematurely , especially by the mid to late 1960's when may Daimler Daimlers in the home market had been withdrawn from service.
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