Enviro 400 Dennis Chassis Variants

[TR673]

Can anybody shed any more light onto the specifics of the various chassis types ADL have used for Enviro 400s over the years? It’s one of those questions that an internet search was reasonably never going to answer, because although E400 chassis can be broadly divided into Trident, E40D and E40H, there are an awful lot of unexplained sub-variants when you look closely.
(Ignoring chassis built by other manufacturers, Volvo, Scania...)

I know some of what I’m about to describe here is bordering on mind-numbingly technical, but now I’ve noticed these differences I’m curious.

Diesels:


Variant A (example MX06 XAJ)

• Registrations between 2005-2007
• Radiator grille on nearside
• Old-style dashboard

The earliest Enviro 400s were built alongside later ALX400s, are Euro 3 and use the 8.3 litre engine. Is it correct that the chassis of these are completely unchanged from the standard Trident and the only difference between one of these E400s and an ALX400 is the facelifted body?
(And if so, why did Stagecoach switch to 19XXX numbers instead of continuing the Trident 18XXX system?)


Variant B (example NK07 HBF)

• Registrations between 2007-2009
• Radiator grille on nearside
• Old-style dashboard

Euro 4 Enviro 400s have a smaller 6.7 litre engine and an AdBlue filler flap on the offside. The chassis model is still referred to as ‘Trident 2’ though, so is the only change the engine or did the chassis change in any other way?
Also, for non-ADL bodied examples (e.g. London DOE class) why are they referred to as “XXX bodied Enviro 400” and not “XXX bodied Trident”?
And to stretch the question even further, do Tridents retrofitted to Euro 4 (with AdBlue) only have AdBlue or do they also get engine swapped to the 6.7 litre?


Variant C (example LX09 FCE)

• Registrations in 2009
• Radiator grille on nearside
• New-style dashboard

Now this is confusing, as the radiator is on the nearside, but the dashboard has been updated to the new oval shape, on an otherwise pre-facelift bus. At what point does the designation switch from a Trident 2 to an E40D? I’d assume radiator position is a more important factor than dashboard?


Variant D (example SN10 CFD)

• Registrations between 2009-2015
• Radiator grille on offside
• New-style dashboard

This appears to be a standard E40D, the radiator is on the offside now and the shape of the engine access panel has changed, while the front end has the new-style bumper panels and running lights. Less obviously the front axle has changed to a different design (the hub is visually different). Is the E40D a completely redesigned chassis, or just a mildly updated Trident 2 with a new name?


Variant E: (example FX60 HFH)

• Registrations between 2009-2012ish
• Radiator grille on offside
• New-style dashboard

Clearly Stagecoach opted to keep the pre-facelift front ends on their later E400s, but they appear to have got a special variant of the chassis too that still uses the same pattern front axle. Or does anyone know if the E400 was available to specify with different types of front axle at this time? By 2014 Stagecoach are using the updated front axle.


And to mention the E400 MMC, the chassis on these are still called E40Ds, so aside from now being Euro 6 is there any difference at all between a ‘classic’ E40D chassis and an MMC E40D chassis?


Hybrids:


Variant F (example MX60 BVH)

• Registrations between 2010-2011
• Radiator grille on offside

These early production E40Hs have the main engine grille on the offside, but were only built like that for a year or-so. Somewhere I heard it mentioned the E40H is based off the Trident and not the E40D – is this true? Also, unlike the E40D, the engine compartment access panels on both sides have the Trident-like stepped shape.


Variant G (example YN61 BFP)

• Registrations between 2011-2013
• Radiator grille on nearside

Mid way through the ‘61’ registration series the large grille switches to the nearside, and the offside access panel becomes rectangular. Why did this change happen? Again, the hybrids were only produced in this format for a couple of years.


Variant H (example SN14 TYB)

• Registrations from 2014 onwards
• Radiator grille on offside

By 2014 the hybrid has changed again with the grille swapping back to the offside, but now it’s taller and situated lower reminiscent of a DAF DB250. Another big change is the main engine bonnet on the rear, which is now huge like the one on a Scania. MMC/City bodied E40Hs also have this layout. I guess my question here would be, why did they change it a third time?


It seems strange to me that in the space of only a few years the hybrids went through several major changes under the skin, but no enthusiasts so much as refer to them as E40H Mk1/2/3s, let alone explain why. Even for the diesels it feels like some details have never been seen outside of the manufacturer’s manual, because I can’t find a trace of them anywhere.
So if anyone out there has trivia regarding ADL’s chassis used on Enviro 400s – diesel or hybrid – I’d be welcome to hear it.


(here are pictures I've taken of each variant, but for some it's worth searching up views of the other side or rear - especially H)

 

[Shaw S Hunter]

I would suggest that the answer is that the level of detailed knowledge you have described is actually of little concern to the overwhelming majority of those with an interest in buses, whether as industry professionals or enthusiasts. That's not to say it isn't worth knowing, more that the level of interest is such that there is little published outside of manufacturers' brochures/specifications because for the most part who cares?

And it's nothing new. Back in the days when I was an active spotter (1980s - I feel old!) like most I considered types like Atlantean, Fleetline, VR, National, etc to be somewhat homogenous other than there being far more bodying options for most types. To the extent that I didn't care that the official chassis code prefixes for the Atlantean and Fleetline changed during their production span (PDR to AN and CR(G or L) to FE respectively).

As I find myself starting to rekindle my interest somewhat I find a similar situation. Just how much difference is there really between the different Volvos, it's not even as if the numbering was changed in sequence! And even worse Transdev refurbished some Eclipse Gemini vehicles to mk 2 standard but that only really affected the dash. Never big sellers here but just how many different generations of Citaro have Daimler-Mercedes produced and how many enthusiasts could recognise them all?

I hope this doesn't come across as unnecessarily negative, more a reflection of the reality that I perceive. In the meantime if you do find out the information you're looking for get it posted somewhere so that anybody else with the same queries has an easier time of it!

 

[ZJ517]

In fairness, there are technical nerds like myself who are interested in the mechanical design and TR673 should not feel left out here...!

I cannot elaborate on many of the changes you have listed. The short answer I think is that the basis structure of both diesel and hybrid chassis are largely unchanged, at least I believe ADL thought so that they remained numbered under the same VIN sequence as the original Trident. With respect to the dashboard change, I assume this was a minor design change - much in the same way as Volvo moved to a new dashboard for the post-2004/5(?) B7TLs and B7RLEs. On the subject over changing the chassis designation from Trident to E40D, this is not apparently linked to any design changes listed - the first example so designated was part of a large batch of Stagecoach 2009/10 order, which carry both E40D/Trident chassis plates.

Variant H shall be easy to explained as they shall be the Euro 6 variant, with a subtly longer rear overhang (presumably to accommodate the slightly larger engine). Only Stagecoach London ever took this variant and they are all under the SFD1GZ chassis variant. Euro-6 diesel E40D variant also featured the extended rear overhang.

On the changes under variants D (for the E40D) and H (E40H), probably the best guess is to do with the modification to EEV standard (i.e. Euro V) which, for SCR engines like the Cummins units used by ADL, from what I recall, required more Adblue exhaust treatment.

 

[Pyewipecarshed]

When ADL updated the front end they included a recess under the headlights into which could be inserted a line of LED running lights. Not all operators specified them, whilst Stagecoach went one better and refused to have the new front panel at all (as you have noted above). They continued to specify the older style panel until they stopped taking original style E400s and went onto MMCs. I'm guessing this was to standardise spare part stocks.
As for the front axle I'm not sure examples D and E are different. Looking at photos of SN10 CFD on Flickr, the appearance of the front wheel changes with how it is painted. FX60 HFH is carrying a wheel embellisher in the photo (as do most Stagecoach E400s) which radically alters the appearance of the wheel. I've found a photo on Flickr of it when new without the embellisher;

Group Enviro400 Lineup 19684-6 FX60HFF-H (4)

Explore dearingbuspix's 158942 photos on Flickr!

www.flickr.com

As for the chassis designation, Matt Wharmby in his book The London Enviro 400 states that it changed from E400 to E40D when changes were made to meet European design regulations, although what these were is not specified.

 

[MotCO]

Did any vehicle regulations change during this time, which necessitated a redesign? TfL introduced some specific requirements.
The other issue is that there is probably constant research and development. Cars, whilst looking similar on the surface, have many changes under the bonnet and skin during their production run. The changes on buses may just be a bit more obvious from the outside.

 

[Surreyman]

You don't mention chassis lengths, I have always assumed that there have only been 2, basically a standard length - approximately 10.5 metres- ish and the Long version - 11+ metres (they have probably varied slightly over the years) & Yes, before anyone mentions it, I know that the actual body lengths will have varied over the years.
Without checking, I assume that ADL have produced a 12 metre 3 axle version? - for the far east?
British Bus publications have detailed 9+ metres in some of their publications - I assume this a straightforward error?

 

[ZJ517]

You don't mention chassis lengths, I have always assumed that there have only been 2, basically a standard length - approximately 10.5 metres- ish and the Long version - 11+ metres (they have probably varied slightly over the years) & Yes, before anyone mentions it, I know that the actual body lengths will have varied over the years.
Without checking, I assume that ADL have produced a 12 metre 3 axle version? - for the far east?
British Bus publications have detailed 9+ metres in some of their publications - I assume this a straightforward error?

The tri-axle is Enviro 500, a completely different chassis with a different engine mount.

As for lengths of the E400s, there are actually 3 versions - 10.3m, 10.9m and 11.5m. Strictly for the original E400s, these carry VIN# starting with SFD1, SFD4 and SFD6 respectively. Similar wheelbase option remains in the MMC and City version, albeit being typically 0.2m longer (with different VIN prefixes).

 

[37114]

When ADL updated the front end they included a recess under the headlights into which could be inserted a line of LED running lights. Not all operators specified them, whilst Stagecoach went one better and refused to have the new front panel at all (as you have noted above). They continued to specify the older style panel until they stopped taking original style E400s and went onto MMCs. I'm guessing this was to standardise spare part stocks.
As for the front axle I'm not sure examples D and E are different. Looking at photos of SN10 CFD on Flickr, the appearance of the front wheel changes with how it is painted. FX60 HFH is carrying a wheel embellisher in the photo (as do most Stagecoach E400s) which radically alters the appearance of the wheel. I've found a photo on Flickr of it when new without the embellisher;

Group Enviro400 Lineup 19684-6 FX60HFF-H (4)

Explore dearingbuspix's 158942 photos on Flickr!

www.flickr.com

As for the chassis designation, Matt Wharmby in his book The London Enviro 400 states that it changed from E400 to E40D when changes were made to meet European design regulations, although what these were is not specified.

There were 2 types of front axles used, ZF and Dana Spicer. The ZF hub stands proud of the wheel face (i.e. through the central cut out of the wheel,) the Dana version is recessed. There seems to be no logic as to which Front axle was used.

 

[MotCO]

The tri-axle is Enviro 500, a completely different chassis with a different engine mount.

As for lengths of the E400s, there are actually 3 versions - 10.3m, 10.9m and 11.5m. Strictly for the original E400s, these carry VIN# starting with SFD1, SFD4 and SFD6 respectively. Similar wheelbase option remains in the MMC and City version, albeit being typically 0.2m longer (with different VIN prefixes).

Wasn't there an Enviro 400XLB for Edinburgh and Cambridge, which had 3 axles?

Also, I think the 10.3m Enviro 400 was meant as a competitor to the Omnidecker, which was more manouverable around tight corners. Don't know how popular it was (the Enviro that is - we all know how popular the Omnidecker was!)

 

[ZJ517]

Wasn't there an Enviro 400XLB for Edinburgh and Cambridge, which had 3 axles?

Also, I think the 10.3m Enviro 400 was meant as a competitor to the Omnidecker, which was more manouverable around tight corners. Don't know how popular it was (the Enviro that is - we all know how popular the Omnidecker was!)

The XLB is just the bodywork built on Volvo B8L chassis. I thought we are talking about the Trident/E400 chassis here which is two-axle only.

The shortest E400s are largely aimed at the London operational constraints, where longer wheelbase vehicles are not suitable for a significant number of routes. This has been the case since the early low-floor eras where short wheelbase Tridents and B7TLs form the bulk of London fleets, whereas most of provincial operators largely moved on to longer wheelbase equivalent types.