There are variations on a theme, unfortuatly I do not believe there are any that work "out of the box" but I have seen them modified to work, how they did it I don't know! A lot depends on what era you are modeling as this will determine what choices you have.

 

Triang-Hornby produced a mineral set many years ago which had long wheelbase wagons with metal flaps in the bottom of the hopper, tripped by a lever at the trackside.

There were medium grey ones and black ones, and if you took the top off the similar (grey) grain hopper you found the wagon part was the same but with different lettering.

They had coarse scale plastic wheels with divided axles which were a close fit on steel axle pin pushed through the axle boxes.

The couplings were Triang metal tension-lock type held to the chassis by a self tapping screw.

The hopper wagons and grain hoppers were also sold separately.

New wheels would be needed for modern conditions but if you can pick them up cheap enough they are worth having.

Depends what era you are modelling, and how accurate you want to be.

Some ex-LNER 21-ton hoppers with working flaps would suit some older modellers.

 

I've got a bachmann 'Barnsley Main' wagon from my DCC set that has an end tip, side flaps and trapdoors. Shame none of them work!

 

Would I be wrong in thinking that there is something along these lines in the current Hornby range as part of a set ??

Just a thought..........

 

Those who tried the operating hopper wagon from Triang mentioned above may well recall that it didn't actually work too well. The plastic 'coal' was too light, and rather prone to not falling out of the hopper as a result. Loaded with small steel ball, the emptying worked perfectly: but then it was too heavy to be pushed up the ramp, and even on the level the loco didn't have enough power to unlatch the hopper at a realistic speed. If you took a flying run on level track at the unlatch mechanism it would work, but then the weight of the wagon meant you overshot the dump bin...

With rather more experience in bulk materials handling in real life behind me, I have idly mused how nice it would be to make a working model of a Charringtons 'Coal Concentration' depot 18 wagon set, based on the LNER design 21T steel hopper. (This was very much the forerunner of what became the MGR set in the UK.) In 1958 this continuously braked fixed formation coal train really stood out among the standard loose coupled unbraked coal trains moving relatively slowly behind an 8F or 9F.

 

*** Aren't you rather forgetting the 40 ton LMS stonebridge hoppers - pre WW2. These full-train "sets" of bogie hoppers, very like the classic German design, formed a fully braked and quite fast timetabled daily "MGR" type coal train between the North and Stonebridge park Power Station for many years.

Richard

QUOTE (34C @ 8 Jul 2010, 16:30) <{POST_SNAPBACK}>Those who recall the operating hopper wagon from Triang mentioned above may well recall that it didn't actually work too well. The plastic 'coal' was too light, and rather prone to not falling out of the hopper as a result. Loaded with small steel ball, the emptying worked perfectly: but then it was too heavy to be pushed up the ramp, and even on the level the loco didn't have enough power to unlatch the hopper at a realistic speed. If you took a flying run on level track at the unlatch mechanism it would work, but then the weight of the wagon meant you overshot the dump bin...

With rather more experience in bulk materials handling in real life behind me, I have idly mused how nice it would be to make a working model of a Charringtons 'Coal Concentration' depot 18 wagon set, based on the LNER design 21T steel hopper. (This was very much the forerunner of what became the MGR set in the UK.) In 1958 this continuously braked fixed formation coal train really stood out among the standard loose coupled unbraked coal trains moving relatively slowly behind an 8F or 9F.

 

Deliberately so. BR management (bless its' cotton socks) stuck with four wheel wagons for defined route bulk coal traffic.

When dug into by economists what emerges is the following tragedy. There are nationalised coal mining, railway and power generation industries. All their separate managements are tasked with keeping expenditure in budget. In order to obtain the overall benefit of the largest wagon type possible being used for MGR, the mines must revise their loading facilities, the railway must build a more expensive wagon, the power station reception facilities have to be significantly upgraded. All three management parties have to act in concert, if the economy of more efficient bulk movement is to be obtained; and if any one of the parties refuses to sign up, all is lost. So instead of the best solution - big bogie hoppers - we got a poorer solution which allowed one of the managements concerned to minimise its' expenditure. It took privatisation, coming nearly forty years later, to do the job: EWS ordered the highest capacity bogie hopper possible in the UK loading gauge as one of their early actions...

 

Thanks everyone for your feedback on this. Sounds like I will probably have to make my own.....wish me luck!

 

Factors to consider.

The load that is to be dropped. The particle size, shape, and density will determine what vehicle interior shape and exit aperture are required for reliable operation. Best to determine this by experiment before embarking on model building.

A reliable latch design that requires significantly less force to operate than one that will derail the vehicle. It needs to be positively secured if you intend running the vehicle, to avoid unintended opening; and ideally to be auto latching when the drop door(s) are returned to the closed position.

I would go looking at websites like the NMRA for links to projects; someone somewhere in the USA will have done this.

 

actually came across three brand new (or they were years ago) triang drop wagons on a stall at chasewater today but the collectors edge was definatley illustrated in the price about £15 a shot