(first posted 8/6/2016) A majority of our Bus Stop Classic posts to date have focused on motor coaches used in the US and Canada – we’ve yet to look at a bus from our other North American neighbor – Mexico, and as I started reviewing possible candidates, one clearly stood out – the Sultana TM 40 – a 4 axle intercity bus with steerable front tandem wheels.
Coaches with tandem front wheels, which allow for heavier loads on weight-restricted jurisdictions, were once a bit more common in Europe, Asia and other parts of the world, but increasing weight limits and lighter construction techniques have made them mostly irrelevant.
A little history first – Sultana coaches were built by a Mexican transportation conglomerate – Trailers de Monterrey, established in 1952 that built trailers, trucks and buses. It is now called Groupo Industrial Ramirez. The company’s founder, Mr Ramirez, is in the middle of the above photo.
Sultana Super Integral
Brill ACF IC 41
The TM 40 was preceded by several other Sultana models; here is a “Super Integral” which bears a close similarity to the ACF Brill IC 41 coach.
GM PD 4103
This is a later “Integral” which somewhat resembles a GM PD 4103.
Sultana TM 40
GM 4501 Flxible VL-100
The TM 40’s inspiration seems to emanate from two mid-’50s buses; the GM 4501 Scenicruiser and Flxible VL-100 Vistaliner.
Interesting in that the company’s main competitor, Dina, license built versions of Flxible’s coaches in the 1960’s. This is a Dina “Olympico.”
The TM 40 first rolled off the assembly line in 1963 and was built up to the late ‘70s. It used mostly GM engines shipped from the US – typically the 8V71, with a Fuller “Road-Ranger” transmission.
Like its US counterpart, it was air-conditioned and had a restroom. Some also had small galleys that could prepare buffet meals for long trips. The SP stood for “Super Panoramico”
The coach was routinely used on the Mexico City to Acapulco route – in the ’60s and ‘70s about a 10 hour run.
Sultana supplied buses for much of Central and South America and my understanding is several are still in use in smaller Central American countries.
Though drawing inspiration from other models, it’s a truly interesting design…
Interesting article and pictures. My wife and I rode in a Dina Olympico bus once in the early ’90’s – it took us from the Acapulco airport to our hotel. I’ve never seen a 4-axle bus.
Thank’s Jim, another great bus read. Tandem axles at the front and at the rear, that always looks impressive and means serious business. Both on trucks and on buses.
I’m not 100% sure, but I don’t think that the Euro-manufacturers currently build a bus with tandem front axles. What I see nowadays is that the top-coach models have a tag axle, steerable and with single wheels, just like the VDL Futura below. All of them with a single front axle. (Photo courtesy of VDL Bus & Coach)
In the ’60s and ’70s the Bedford VAL chassis had tandem axles at the front, but single at the rear, allowing slightly smaller wheels than normal on a coach chassis so less wheel arch intrusion at floor level. The coach in the original ‘The Italian Job’ film is on a VAL chassis.
Another famous VAL is the Plaxton Panorama Elite-bodied one featured in the Beatles production Magical Mystery Tour.
There was the Neoplan Megaliner for the Scandinavian market and some found their way into Serbia, saw one in Vienna a few years back.
PS: And Turkey got some too.
Yes, but is any Euro-bus manufacturer still building them these days ? I didn’t find a bus with tandem front axles on Neoplan’s website, for example. The Skyliner is their top model, same axle-configuration as the VDL above.
No, full air suspension has negated the need of the extra axle to smooth the ride its a weight spreading requirement on heavy trucks due to axle loading regulations never really needed on buses which do not carry much weight.
Thanks Johannes, I didn’t know European manufacturers had stopped making 4 axle coaches – thanks for the info.
That VDL looks like a beautiful bus. Jim.
Beautiful coaches, thank you for the post. Is there a Dina writeup in the future?
That would be interesting, DINA seems like a fascinating company. In a recent post here it was mentioned that DINA also license built Alpine A110s!
Great suggestion Erik – I’ll put it on the to-do list. Jim.
I don’t have an opportunity to post very often at Paul’s site, but I wanted to make a point of complimenting you Jim, on your excellent regular Saturday bus stop classic articles. The quality, completeness, and attention to detail in your articles, and knowledge of the transit industry is really impressive. And supports the high quality writing, and factual correctness, that are hallmarks of Paul’s site. I always make a point of reading your stories. And appreciate the volume of pics you include.
As a student, I recall riding many of the buses you have profiled. Living in Toronto and Ottawa, I mostly experienced the GM old and new looks, the 70s Flyers, the GM Classics, the first Nova low floor bus, plus the articulated GM GMC-TA60 from the early to late 80s. A well as much of the Orion lineup. Including the infamous Orion Ikarus 286. I recall once having to evacuate a brand new Ikarus in Ottawa during a heavy snowstorm when the driver managed to angle the bus so sharply that the bus was pinned forwards against a wall. And had no ability to move further backwards, due to its severe angle.
I have to say that the large improvement by the late 90s for most manufacturer’s models, in comfort, maneuverability, acceleration, braking, and overall experience, was remarkable. Looking back, the GM new looks were appearing badly dated by the late 70s and 80s. Their noise, vibration and ponderous nature, made them a true test of one’s patience as a rider. However, they were still in regular service well into the 2000s. I think I have fondest memories of the articulated GM GMC-TA60. As they were configured with single seats to the left in their front section, providing lots of room. In an era when public transit wasn’t so heavily used.
Congratulations Jim, on a series you should be very proud of!
Thank you for the very kind words Daniel – I’m glad you enjoy them. Jim.
Beautiful Coach and a nice article .
It looks HUGE .
How is it that tandem axles in the front allow for a tighter turning circle than a standard single axle? Are they somehow able to pivot more sharply, or does the rear set of the front pair somehow pull the front ones into the turn? I would think turning radius is determined by the full size of the wheelbase between the front-most set and rear most set. Can someone explain the geometry I’m not seeing?
That’s probably not the case, and I’ve amended the text to reflect that. Dual axles are typical a reflection of meeting relatively low weight restrictions. This 40′ bus was likely quite heavy, and needed the front duals for that reason. I can’t imagine any other reason.
It most certainly is the case. Two lighter weight steer axles are capable of a sharper wheel cut than a heavier capacity single steer fitted with a fat tire.
Sorry, but I don’t buy it. The tires on the front of this bus are just the standard tire size, as were used on single-front axle buses. The only thing that makes a turning circle smaller is a greater angle of the front wheels. Or of course a steerable rear tag axle.
If you’ve been to Mexico, you’d know that these intercity buses don’t traverse the narrow back roads of villages. In almost all Mexican cities and towns, there’s a main highway/road that runs usually straight through town.
These particular buses were specifically designed for long-haul routes on highways, with a luxury level of service. A tighter turning circle was the least of their concerns.
Mexican bus technology was not very advanced, and I strongly suspect these buses were over-built some, meaning heavy. That’s the only reason to ever put dual axles in front.
I appreciate all the inputs on the rationale for steerable tandem front wheels – I think Paul is right and I made a bad assumption when writing the article. I based my assumption on a shorter turning radius on my experience here in Japan where most trucks over 35 ft have tandem steerable front axles. I’ve spoken to several drivers and they related that smaller diameter, thinner front wheels (in tandem due to axle loading) can clear front suspension components and any body work to articulate farther than a single larger diameter and thicker wheel. I thought this was the reason for the TF axles on this bus, but think Paul’s correct – as an intercity bus, it didn’t need this aspect as it rarely ventured into smaller side-streets and given Mexico’s roadways, was over-built and heavy, requiring a tandem set-up for axle loading. Jim.
I drive an eight wheeler Isuzu bathtub tipper on a semi regular basis pulling an eight wheel bathtub tipping trailer most of the rest of the fleet I am amongst are six wheel chassis and maneuver in tight spaces much easier with their tighter turning radius we sometimes have to tip off loads inside buildings with restricted access this task is usually given to the six wheelers due to their better turning radius even more important when you have a trailer hooked on, the extra ton missing from the tare weight allows more product to be carried on the same max loading sticker too. I dont have a pic of the whole thing but thats the front 460hp Giga cab Isuzu it also uses a 18 speed Eaton Road ranger manual trans as does nearly everything.
Jim, I can see from your exposure to the Japanese trucks you described why you would make that connection. I’m not that familiar with those, but having been to Japan, maneuverability is a critical issue, and although I’ve not heard/thought about it before, the set-up you describe, with smaller, narrower and tighter-turning front wheels makes total sense. You’ve expanded my understanding about how truck design is localized for the prevailing conditions.
I guess the pre-amendment text claimed these buses had dual steers for maneuverability. The point still stands that when lower capacity twin steers are chosen over a heavy single it’s in the name of max wheel cut.
Now giving this specific application some thought I’d postulate that using two of the lighter axles just worked out better economically. May have been cheaper up front but certainly easier to get your hands on both the original unit and replacement parts, (the 12,000 lb steer axle is a sort of de facto North American standard.) Same goes for tires and wheels, with the added bonus that a single size spare could be used on any position around the bus in case of a flat.
george: The point still stands that when lower capacity twin steers are chosen over a heavy single it’s in the name of max wheel cut.
You’re making a blanket statement that you can’t back up. Certainly not in the US, where dual front axles have always been extremely rare, and only used in certain states (and in one particular Canadian province) that had/have particularly low axle weight limits. I’d like you to give us some examples of NA trucks or buses with dual steer front axles for the specific purpose you stated.
That may be the case in certain parts of the world, like the examples Jim gave for Japan. But it’s just not a universal reality.
Having done a bit of research, here’s the reality, as least as it applies to the US: Western Star (a Daimler subsidiary) is apparently the main NA manufacturer to offer a OEM dual front-steer truck (image attached). The advantages are better weight distribution, because more weight can be carried on the two front axles. It does also result in potentially improved maneuverability because the twin axles can be combined with a shorter wheelbase. A typical single front axle truck requires a longer wheelbase to carry the same weight, to distribute more of it to the dual rear axles.
That helps explain the dual front axles on the Japanese trucks Jim was talking about, as they undoubtedly are COE trucks with a relatively short wheelbase. A short wheelbase puts more weight on the front axle(s). In the US, almost all trucks are conventional, with long hoods, which helps distribute that weight to the rear. But ultimately, the ideal weight distribution comes from dual axles front and rear, with the front axles set well to the rear, so they can carry more of the full weight. That solves the high axle loading issue of a single front axle, and also reduces wheelbase for better turning.
Once again: the only thing that improves turning radius is either/or: shorter wheelbase (which dual front axle can facilitate) or increased front wheel angle at full lock. By themselves, duals do not intrinsically improve turning radius.
Forgot the image.
Also, as per Western Star, the turning circle of a dual front axle truck is a component of the distance from the front-most axle to the middle point of the two (non steered) rear axles. The second front axle cannot actually improve the turning circle, as the front-most (outer) axle defines that. Only moving the axles back can do that.
The only heavy vehicle companies I know of still building tandem front steering axles setback close enough for better maneuvering is Marcopolo who builds buses and motorcoaches plus Oshkosh (based out of the United States) who currently builds military vehicles.
8 wheelers have larger turning circles than 6 or 4 wheelers especially on American chassis and whats true for trucks likely holds for buses.
Thanks all for weighing in on this and clarifying for me!
I didn’t know Mexico had such a conglomerate, nor that they built buses, so thanks! It again shows how firms don’t need to be major worldwide players to find niches in the truck & bus markets.
My surprise is because I see many intercity motorcoaches serving Mexico here, but foreign makes like Volvo, Van Hool, et al.
Slight nit the tight turning circle you mention is not the result of the twin steer axles but of the single tyred rear axle allowing that axle to skid in tight turns, this configuration is called a Chinese eight as opposed to a regular eight wheel setup with twin tyred rear axle and just to blow your entire theory out of the water a six wheel configuration with single steer axle turn much tighter most city buses where this is required run a Chinese six configuration single twin single tyred axles down the lenght of the vehicle.
You have good points.
For citybus that Chinese six wheel configuration is great, up to 40′ that is…..
Beyond 40′ that configuration becomes impractical. An 8 wheel configuration is better beyond 40′ for that reason. In the States 45′ is the sweet spot for a 3-axle coach (especially since you don’t see 40′ three-axle coaches built that much for the States anymore). Anything larger larger than 45′ (in my opinion) requires a 4th axle. But if a company wants a 45′ coach with a shorter wheelbase for minimum bottom outs and a better turning radius an 8 wheeled 4-axle coach works in that situation too.
When we lived in SoCal, we often got down to Tijuana, and I used to love the buses there. They were gnarly, noisy and smokey; mufflers were obviously seen as an unnecessary affectation. I’m trying hard to remember if I saw one of these; possibly. Dinas were most prevalent.
Thanks Jim for this look at a bus I had long forgotten about.
I once followed a Mexican bus on I-5, a private one evidently hauling a Mariachi band or something, whose exhaust was amazingly loud. It overtook me, then settled back down to my speed, so I kept falling back trying to avoid his noise yet found it annoying even several hundred feet back! I don’t know what occult acoustics made this possible.
I never saw one, but those four wheels upfront sort of reminds me of the bus from “The Italian Job”-the original, not the terrible remake.
Italian Job (according to an imdb comment) Bedford VAL14 with Harrington Leigionnaire bodywork
I can see that four axles would be an advantage in Peru.
More axles = more brakes.
Our company did some work in Peru in the 90’s and it was unofficial policy to not ride in two axle buses on the mountainous roads to the mine site.
Very interesting coach! Use of the 8V-71 Detroit is not a surprise considering its widespread use in domestic buses, but use of the Roadranger transmission is. I guess given the operating conditions the Sultana would likely see (not to mention its weight), a non-synchro twin countershaft transmission would be an advantage.
You’re right Bob – I thought the use of the Roadranger was unique also – I’m assuming it must have been significantly cheaper than some of the other alternatives,or Sultana just decided to use it as it was most likely what was used in the trucks they built. Jim.
Great-looking buses; something about the dual front wheels, the headlight arrangement, and the angle of the windows make these appear so much more “exotic” than a Scenicruiser.
The 4-axle Murrays coach/bus shown is in Australia, but it is very unusual. Apart from a handful of examples I can’t say there are any other twin-steer buses here, and I wonder if it was a longer-than-usual model to require the extra axle. On the other hand despite air suspension, there would still be a smoother ride than a single axle.
Also is it just me but the Super Integral doesn’t really look like the Brill below it?
The Murray’s coach was usually long for its time. Between 48′-50′ long.
Megabus Gold uses a 48′ VanHool double-decker sleeper coach with a single front steer axle. I don’t understand why Megabus did not request VanHool to build tandem front steer axles. Maybe they were able to save money with a high-tech single axle. No different than Airlines currently saving money by ordering large aircraft with twin engines instead of quad engines…
Marcopolo builds tandem front steer axles for their double-decker coaches.
The neat thing about the Neoplan Megaliner a lot of people don’t know is that its rear drive axle also steered like its rear tag axle did! However the drive axle only offered passive steering given the transmission was right there between I’m guessing.
Pretty unique and haven’t seen no one do that to a bus or motorcoach since.
I drove busses for LCMTA for 27 years, always wondered what it would have been like to drive a four axle bus, just a note as i scanned a few coments, this bus is in fact 15 (fifteen) meters in length. There is a web page Sultabus which is in Spanish but has quite a large following would be worth a look to know more.
I’ve read that 4-axle intercity buses are still built for use in mountainous Latin American countries, where the extra pair of front tires is considered a safety and stability feature: think Peru, you know? Plummeting high-speed descents down narrow sharply curving roads, brutal potholes that can take out a steer tire, that sort of thing.
I worked for Greyhound bus back in the 70’s. For a time we had to limit fuel in our MC7-8’s that were on runs that travelled into Missouri. Missouri was really sticking it to us for being overweight on the front axle. Most states would allow a certain leeway but something changed in Missouri and every bus was being weighed and ticketed.
The fuel tank ran across the bus directly behind the front axle so the fuel load was a factor on the front axle. The trick was guessing how much fuel to put in as there wasn’t any fuel gage. I would guess management had probably posted a bulletin on fuel amount for these routes.
Magical Mystery Tour (replica) bus:
These buses posts by Jim are awesome.
Never saw a Sultana, the name only already makes for something exotic … and the design is really fine too, on my opinion.
In comparison to Brazilian buses from the 60s and even 70s it looks more modern and sophisticated… except for the unibody Mercedes-Benz we had here
I have many fond memories of riding in Sultana TM 40s to Acapulco and Mazatlan from Mexico City in the 70s, 80s and 90s. I loved to sit in the front row so I could watch the drivers go through the gears and high and low range as we went over the mountains. The drivers were virtuosos! Keep up the good work.
Very interesting article about these buses… some being really huge! Was the Fuller Road Ranger transmission in 1963 automatic.?
I recall going on a field trip with my elementary school class to Boston in 1968. The bus I was on was a manual transmission, probably 4 or 5 speeds. I think the whole fleet or 3 or 4 were – I remember being home when they passed my house going back to their lot, heard the manual transmission characteristics.