We have had a request from overseas that I wonder if somebody can answer ?

What is the axle weights for an RML ?

I believe that the correct terminology is permitted axle weights.

Thanks

Andrew Morgan

My bus number (if any): RM1368

I rang VoSA Technical at Bristol about ten years ago about this. This seems to be a somewhat murky area since nothing appears to come up with answers that tally with other criteria. Somewhere I have it written down, but it will probably be quicker to ring again. Alternatively a tester at an ATF should be able to access the Technical Information Data records from the DTP number. Another alternative is to get the data off an RM which has been tested as an HGV which will therefore have a plating certificate. The person I spoke to at the time owned a single deck RM and was very helpful. I can't recall the axle weight but he did say that the design gross was the same as an RT at 13.25 tonnes I know that the figures he gave me did not tie in with LT Vehicle statistics chart 0392 for the front axle. This shows the RML front axle as carrying nearly 5.5 tons with the assumed total passenger weight of 4t 12c 2q. This is a conflict with the maximum tyre load rating for both a 900x20 14 ply and a 10x22.5 14 ply tyre. I think the answer I was given was front axle 4.5 tons rear axle 8.5 tons.

The following data is taken from:-

LT Chiswick Works
Vehicle Statistics Information
Chart No 0397
Circ 1979

RML Vehicle Axle Loadings
Figures for Unladen Rating only

Front Axle (Boat):- 3Ton 12Cwt 1 Qtr 17lbs
Rear Axle:- 4ton 1Cwt 2 Qtr 12lbs

Total Unladen Weight:- 7Ton 14Cwt 0 Qtr 1lb

My bus number (if any): Ex LTE Bus Engineering

What roy says above tallies with a conversation I had with a certifying officer at Mitcham many years ago when I took Simon Douglas-Lane's RT for certification.

The CO done some calculations nd said the RT was overweight on the front axle with 900x20 tyres and it would not be leaving with a Certificate of Initial Fitness. I told him it should do because there were 4,700 of them built and all ran on 900x20 tyres. He was adamant his calculations were right. He'd done the London Country bus a year or so before and that had to be fitted with 1000x20 tyres on the front, which then fouled the chassis on full lock.

At that time there were few RTs left in service, so I got the details from one of Blue Triangle's buses and gave them to the CO.

He went away and looked on the computer, made some phone calls and came back with the CoIF.

Otherwise the best I can offer is the DTP brake code for RML2532 which is 127202. any test facility ought to be able to give the unladen axle weights from that number. Unladen weight is about 7765kg. RML 2532 is a refurb with Cummins C series and modern lightweight seat cushions and runs on 1000x225 tubeless radials.

What is interesting and confusing is the following:

test station A Front axle unladen weight 4427 kg, rear axle 5157kg

test station B Front axle unladen weight 3870 kg, rear axle 4130kg

both using the same DTP number!

British Standard/EU passenger weight is now 66kg if I remember correctly, so passenger load is max 72+5 standing + 2 crew=5214kg, + UW 7765= GLW 12979kg.

Weight of bus per passenger is UW 7765 divided by 79 passengers = 98.29kg of bus per passenger, arguably the lightest of any large bus per passenger/kg..

But quite how this would spread over the 2 axles is a mystery. :)

My bus number (if any): RML2532

Based on the above information, for Class 5 MOT purposes, an RML should be tested on the basis on a ULW of 7824KG (7 tons, 14 cwt converted to metric) plus a load of 4572KG (72 x 63.5kg) = GVW of 12396KG.

The first three characters of the DTP brake code are the GVW so, for class 6 purposes, they are saying 12700KG for an RML. With five standing (another 63.5 x 5) then 12,700 seems to be spot on with what I would expect.

Questions:

1) Was 7824KG the marked ULW on RML's when they were last in LT use?
2) What GVW's are class 5 testing stations using for RM's / RML's?
3) Are all class 6 tested RML's all being tested on the basis of a brake code of 127202 or are there variations, assuming they all still have 72 passenger seats?

The brake testing computers for class 5's give a % of GVW whereas, if one wheel locks, for class 6's they give a % of ULW. If no locks they calculate using GVW. This explains why class 6 brake testing is significantly easier to pass in the "one or two locks" scenario. Three locks (with less than 30% imbalances) always gets you a pass with either test.

Nothing particularly to do with Routemasters but the hopeless inconsistencies between testing stations conducting class 5 tests has been a topic of interest to me for several years ever since I saw an RT "passed" with an efficiency of 31%, the tester inputting the ULW into the field marked for GVW on a class 5 and it calculating 45%!

My bus number (if any): None that begin with RM...

My understanding of Andrew's question is that there has been a request from abroad relating to the maximum permissable weight allowed on each axle.Unlike the Routemaster, modern buses and HGV have a manufacturer's plate attache to the vehicle which lists the these weights in columns & rows: Design max each axle, design overall GVW. In many cases these figure exceed the weight allowed in the UK. Some duplicate the UK figures, others don't. HGV have a separate 'ministry' plate with All this information on it, this is a VTG 6, these vehicle are also issued with a VTG7 which has the same information on it but adds the tyre sizes which also determine axle weights.

The original request is probably because a foreign vehicle testing organisation will not test a bus without written evidence from an official body detailing what these safe and legal limits are. Those figures have nothing to do with LT's recorded data, this was achieved by loading to an assumed passenger weight not what was legally or structurally correct.

The 72 in the brake code 127202 does not refer to the number of seats. The Garage Equipment Services website had a multi page link explaining Brake test prints out, Front Wheel Allownace for HGV, and Brake codes .

ATFs use a variety of brake codes for the RM series when conducting class V tests. Generally only DVSA Testers have access to full DVSA vehicle information. Some ATFs use a calculated weight using the ULW written on the side of the bus others use the actual recorded Unladen axle weights recorded by the RBT machine. This figure is supposed to be accurate ,but many are not. It may be necessary to produce a weighbridge certificate for the unladen bus, this is unlikely to agree with the legal writing.

About ten years ago I devised a spreadsheet to calculate axle weights for the RM and RML according to a variable input for the passenger weight in each seat. This is reasonably accurate in theory, but it was compiled on measuremants taken rather than a structural drawing, and was based on an assumption of the point on which the passenger weight transfers to the seat mountings. Apart from the latter the information required is all available. I simply can't be bothered to spend the time necessary to rewrite this more accurately when it is for other people's benefit. What it does prove is that these buses are likely to be grossly overloaded when carrying a full load of men.

But the above calculations forget that there's 2 crew members required on a Routemaster.

Wasn't the EU passenger weight increased a couple of years ago to 65kg to allow for larger passengers (or bigger luggage) these days? I know it was altered but can't remember from what to what.

It could be the 7765kg uw is for the Cummins engine versions, the Cummins being smaller than the AEC590 is likely to be lighter. Also modern seat materials are a lot lighter than the original Dunlopillo and horsehair types still found on unrefurbished buses.

My bus number (if any): RML2532