Review: Roundhouse Darjeeling C Class Pacific

01 November 2022
Alan Regan takes a look at the Roundhouse Engineering model.

On 1st January 2020, in a break with tradition, Roundhouse announced three locomotives to be delivered over the coming three years. The Darjeeling C Class Pacific was the third.  Its designer described the decision to model the prototype as a 'no brainer', filling a gap in the Roundhouse Darjeeling Himalayan Railway stable. But, before looking at the model, a little about the prototype.

The DHR placed an order in May 1913 with the North British Locomotive Company in Glasgow for two Pacific tender locos to run on its new Kishenganj extension across the plains of West Bengal.  The locos were delivered the following year and immediately put to work on the 70-mile branch.  They became redundant when following partition, the branch was converted to metre gauge, so were used elsewhere in the DHR system.  By 1969 they were both out of use.  They have separately been preserved as static exhibits, one at the Nehru Science Centre in Bombay and the other at the North East Frontier Railway headquarters in Guwahati.  There were relatively few alterations to the locos during their lifetimes.  The most obvious changes were replacement of the original oil lamps with electric lamps and a supporting steam generator, replacement of the Wakefield lubricator with a Detroit hydrostatic lubricator in the cab and a change to the whistle.  The model reflects the loco as delivered.

So, to the model.  Build quality and finish are what I’ve come to expect from Roundhouse.  The smokebox and cab roof are satin black and the rest is gloss finish, either black or body colour, Deep Bronze Green in the case of this loco (all standard Roundhouse colours are available).  There’s rivet detail on smokebox and firebox, dummy mud hole doors, lost wax castings for boiler fittings and couplings and lots of detail on the bogies and pony truck. 

The only plans available to me whilst preparing this review are from Halfway to Heaven, Terry Martin’s superb book on the DHR.  As far as I tell, with the exception of frames, bogies and pony truck being wider than the prototype, so that the loco can be set to 45mm gauge, the model is a faithful reflection of the 2-foot gauge prototype.  The boiler sits low in the frames, so an unusual but prototypical arrangement is that the lifting arms move via linkages either side of the frames, attached to a weight shaft low in the frames and between the middle and third driver.  This is driven by a servo in the dummy ash pan, which like the regulator servo is connected to the receiver in the tender.  These connections need to be made at the same time as the tender is coupled to the loco.  They are colour-coded and on opposite sides of the drawbar, so difficult to get wrong, but I can see some owners buying or building a cradle to carry the loco, so that this only needs doing occasionally.  The regulator servo, which is a tiny HS‑ 5055MG unit, sits in a bracket under the cab roof and directly above the regulator.  It’s hardly visible unless you’re able to peer up into the roof space from track level.

The controls are readily accessible, but the cab roof needs to be removed for servicing.  Secured either side by tabs and magnets, it’s easy to take on and off, and the dummy coal load in the tender is a convenient place to put it during servicing.  New for this loco is a slim displacement lubricator which is the height of the cab, drains under the footplate and sits in the left-hand corner when viewed from the rear.  It carries sufficient steam oil for a single run, so needs draining and refilling each time.  The sight glass is forward of this but doesn’t protrude beyond the edge of the cab, easily visible yet reasonably unobtrusive.  The gas tank, which is the standard Roundhouse cylindrical fitting, sits in the right-hand corner of the cab and is just visible through the cab window.  This will keep the burner going for 30-35 minutes, assuming the gas isn’t turned too high, resulting in needless blowing off.  The gas control valve is readily accessible so it’s easy to control usage.  The loco has a huge boiler, 420ml, the largest ever fitted to a Roundhouse loco.  The downside is that it takes 8-10 minutes to heat all this metal up and raise steam, the upside is that if a run is started on ¾ gauge glass, there should be no need to replenish water.

There are two ways to fill the boiler.  When the loco is cold, the safety valve and the knurled cylindrical plug that it sits in, both under the removable steam dome, can be unscrewed and a syringe used to add water.  With the loco in steam, you can use the standard Roundhouse filler in the cab, between the steam turret and the gas tank.  A water bottle and flexible pipe are supplied to do this.  However, if you get the water level right at the start of the run there should be no need to use it.  I ran the loco several times whilst writing this review and found that, prepared as I’ve outlined, after the loco had raised steam and I’d cleared condensate from the cylinders, if I turned the gas off, replenished it and lit up again, I was off and running in a trice and the gas would last for 30+ minutes.  My testing was outside in temperatures between six and twelve degrees.  The milder it was, the longer the gas lasted, though I stress that I did my best to avoid the loco blowing off and I never started on less than ¾ glass.

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Testing was conducted in winter conditions with primarily wet rail and low temperatures.  The loco never failed to steam and even though it has an open cab, wind and rain (there was plenty at times) didn’t affect it.  This is a Pacific pulling a heavy tender and on wet and greasy rail, haulage capacity up inclines was around half that achieved on dry rail.  All Roundhouse locos are factory tested using a 6.7kg weight on a flat car.  My son and I videoed it pulling more than this weight up 60 feet of continuous 1 in 50 incline on dry rail – see  This was four Accucraft Lynton and Barnstaple coaches and a couple of goods vans, at 7.2kg a little more than the test weight (on level track) in the factory and an appropriate train for such a loco.  The other thing I noticed and appreciated was how gently it would start.  With the regulator cracked open, which occurs at half movement of the stick on the transmitter, steam pressure gradually builds and the loco and its train slowly move off.  The weight of the loco and tender (6kg) means that this also happens light engine.  I work on the Welshpool & Llanfair Light Railway and this is just the kind of start that we try to give our passengers.

This has been an enjoyable loco to use.  It’s easy to manage and if prepared in the right way, your time can be spent running instead of stopping to replenish water and you can also get 30+ minutes running.  The gas control is easy to get at and you can see the gauge glass readily as the train glides by.  The one I tested was very clean and deposited very little oil over the boiler and cab roof.  The only place I really noticed any deposit of steam oil was on the front bogie, which is right under the smokebox, which is open at the bottom, so perhaps not unexpected.  Roundhouse recommends minimum 3-foot radius curves for the Darj C and I think you’ll lose some of the elegance of the loco if you don’t follow this advice.  Having to connect the servo leads between engine and tender is a faff, but I reckon that it you can afford this model, you can probably afford a cradle.