Whilst at Bakewell exhibition we noticed something we had not seen before. It turned out to be a 1960's Diesel Brake Tender !
formatting link
formatting link
What a typically British idea ( I assume ? ). You have a fleet of diesel loco's who's brakes can't cope with the workload so you design and build a 'wagon' with a powerful set of brakes to correct the problem.
I will be looking out for one of these on our next few visits to railway open days.
They must have obstructed the drivers view somewhat but as I understand it they were used primarily on slow coal trains.
They were an everyday sight on the line next to our school from the withdrawal of steam until the Class 40's were released from mainline passenger duties. A Class 40 was heavy enough to halt an unfitted coal train without braking assistance.
It' s been my experience that the things I saw most often on the rail network have been the last things to be produced in RTR form.
On my Guards course I asked about brake tenders, as they's not been mentioned when dealing with brake force calculations. Our instructor/Inspector confirmed that they were indeed obsolete, and mentioned that they were not really a WR thing (courtesy or Mr. Brunel's "Billiard Table"). Their original intended use was to provide extra brake force when descending particular banks. Normally these banks would be opetated on the "stop - appply hand brakes- proceed - stop - let off handbrakes" principle which is obviously somewhat cumbersome. Almost as soon as they were introduced though, fitted heads started appearing (only a few fitted wagons would match the brake force supplied by a tender) so their use was modified to general purpose, often on high-speed (45 mph!!!) services. They were, however, to some extent, redundant right from introduction. They did however highlight how inefficient the brakes were/are on some diesels
- causing light engines to be only allowed to travel at 2/3 of line speed (and even that could be a tad optimistic, as I found out when going light from Tiverton to Exeter with a 33 once...) - I've no idea if the same applied to steam.
It was one of idosynchronies of railways in the UK that continuous braking was not made mandatory for freight trains when it was made mandatory for passenger trains. The private owners and the railways them selves did not want the expense and British Railways was still building unfitted wagons into the 1950's. The brake tenders were needed because the light weight diesel locomotives did not have the brake force of the heavier steam locomotives that they replaced, excepting the peaks and the 40's. Interestingly the Q1 steamers on the Southern had the same problem in the 1940's a very high power to weight ratio which meant they had difficulty stopping the heaviest unfitted freight trains that they could pull.
You could also have interesting discussions about sticking with the vacuum brake for so long.
I think it's an extreme case of confusing cost of acquisition with cost of ownership. But then only economists expect rational behaviour of humans - sure proof IMO that economists are crazy.
It probably made sense at the time slow freight trains and relatively short distances and inertia kept it going. It probably made more sense in the US with longer distance freights than typical in the UK at the time.
I don't think it's about distance, it's about stopping power. Running a train below optimum speed and weight because of inadequate stopping power is costly, regardless of distance.
In the UK, the actual running time of a goods train from A to Z was a relatively small proportion of the total transit time. Most time would be spend re-marshalling at B, C, D, etc en-route. Even in the early 80's trains such as the Carlisle-Eastleigh spent more time being shunted at Westbury that it did travelling from there to Eastleigh, and if anything was for Sailsbury the ratio just got worse. Obviously with the demise of wagon load and almost all freight now being block trains travelling A to Z with no intermediate stops, speed/carrying capacity have become the key factors.
The reason for sticking with vacuum against air was largely cost- a steam loco could provide a vacuum with a simple ejector with no moving parts, whilst air-braking required a pump, and the payment of a licence fee to the American patentees.
A large scale vacuum-fitting programme was instituted as part of the Modernisation Plan of 1955. Most unfitted 'merchandise' wagons were retro-fitted with vacuum gear, but when they came to start fitting mineral wagons, a problem became apparent. Most of these wagons would, at some time, encounter either a rotary tippler (used in industrial premises such as power stations and steel works) or an end-tipper (as used in docks). Both types of installation were found to be incompatible with the various cross-shafts of 'fitted' gear- 'incompatible' meaning 'ripped off' in some cases- and so a large pool of unfitted wagons had to be retained, as BR were unable to compel the owners of the installations to modify them. This situation lasted into the 1980s for the anthracite export traffic from Swansea Docks.
As regards brake-force itself- part of the problem was that trains were initially loaded for what the new diesels would pull, and not what they would stop. I witnessed several runaways in the late sixties/early seventies, as my bedroom overlooked the bottom part of the Llanelli and Mynydd Mawr line- the continuous horn before they became visible was not easily forgotten. For some reason, brake tenders never made it down there, though after I left, I'm told that a short rake of redundant banana vans were used as a fitted head.
My old boss started his career as a cleaner at Tunbridge Wells shed in the
1960s- being permanently short-handed in the south-east, he rapidly found himself firing as a 'passed cleaner. They were meant only to work with a fully- qualified driver, but on occasions he was sent out firing for a 'passed fireman'. They almost came to grief on one turn with a Q1 somewhere in the Weald, working a heavy, largely unfitted freight- coming down-bank towards a small station where the porter also worked as crossing keeper, they saw the signals protecting the crossing were still on, and the gates were shut against their train. Worse, their brake applications were ineffective...The signalman was busy carrying out his platform duties, but was alerted by the whistle- fortunately, he was able to run to the gates and open, but not secure, them as the train passed through at something above its normal speed. Over the next few days, they waited for a 'Form 1' to arrive, but nothing did- when they next saw the 'bobby' in question, he simply said 'what run-through?- you were a bit fast, I'll admit,..You owe me a pint for the white paint to touch up the gate, though.'
That's true world wide. Back in the 70s IIRC, John Kneiling cited a survey that found that a typical UDS boxcar was standing still over 20 hours per day!
He's full of them- still insists that the railway runs on tea and gossip, so gives me a shout when he's on his way on night shift. Another classic was finding himself on the outside of the van door when he was a guard- he'd blown 'right away', and the driver had started to pull off, when Tony realised the van door (which was on the other set to the one he'd worked in on) was secured by a chain on the inside. He stood on the footboard, clinging on to the door handle with one hand and reaching round to try and release the chain with the other- just managed it before the train went under a restricted-clearance bridge. Brian
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.