Speed difference between Hornby Adams Radial and Oxford Rail model

[GWR-fan]

I have had one each of the Southern black Hornby and Oxford Rail Adams Radial tank locmotives for several years,  both purchased new and never used.  This morning I went to test both models for possible sale and found that the Hornby model is a more typical speed demon and the OR model a lot slower on full power.

 

The OR model runs very smoothly and quietly even to the slowest crawl and while the forward speed at full throttle (Gaugemaster GMC-D controller) may be more prototypical,  when operating in reverse it runs marginally slower.  

 

I always thought of the Hornby model as a "copycat" of the OR,  however, when compared,  the Hornby version is miles ahead in looks and performance.

 

Is the relatively low top speed of the OR model symptomatic of the motor issue that plagued early OR models?  There is no smell nor heat generated but the less than ideal top speed (full throttle needed) has me concerned.

[woodenhead]

My Oxford one was slow too, a nice runner.

 

It’s Achilles heel was the stiffness of the  chassis so it could not take any uneven track, a slight slope being enough to lift the driving wheels off the track.

[GWR-fan]

Many thanks.  I decided to set up a "run-in" track to see if the loco needed a decent run to sort it out.  Initially,  I thought the speed difference between forward and reverse direction may be a voltage issue. In one direction the Gaugemaster outputs 12.3 volts and 13.1 in the opposite direction.  However,  turning the loco around made no difference to the reverse operation as even on the higher voltage the reverse was definitely slower than forward direction. 

 

Even after thirty minutes of alternate direction operation there is no heat or smell evident.  The loco is such a smooth silent runner it is a pity that the speed is not as expected when compared to other models,  particularly in the reverse direction.  Forward speed is acceptable if full throttle used.  It does crawl as well as a top quality model.

 

Edit:  I have run the model now for over an hour with no change in performance.  It would appear that the speed is the most the model is able to achieve.  I noticed that if the model is run forward for a few minutes and then reverse,  that the reverse speed is slightly higher than simply selecting reverse direction first.

 

Edit 2:  With over one hour forward running time the motor was barely warm.  However,  running in reverse direction does cause a temperature rise and a possible burning smell, although very hard to detect if burning or if the model simply smells that way.   Pity as the model does run so sweetly in the forward direction, though a little slow,  as it requires full throttle for anything more than a walking pace.

 

Edit 3:  when the motor "warms up" a bit the speed actually increases a little.

Edited Monday at 05:46 by GWR-fan
Additional information

[34theletterbetweenB&D]

The Oxford had 50:1 reduction ratio if memory serves.

9 hours ago, woodenhead said:

It’s Achilles heel was the stiffness of the  chassis so it could not take any uneven track,

A better comparison of the two mechanisms is obtained by removing the carrying wheels, the Oxford was oversprung and slipping almost continuously in the one example I had to look at. 

Once sorted by reducing spring pressure on the carrying wheels it was far and away the more realistic for scale speed running; i.e. modest progress, rather than the Hornby 'High Speed Tank'.

[westernfan]

I have an Oxford model and agree with the comments above. The slow running is absolutely superb, but the pulling power leaves a lot to be desired, wheel slip being all too common an occurrence.  The slow top speed though is, I think okay as it appears quite prototypical.

[The Johnster]

On 21/10/2024 at 12:12, westernfan said:

On 21/10/2024 at 12:12, westernfan said:

I have an Oxford model and agree with the comments above. The slow running is absolutely superb, but the pulling power leaves a lot to be desired, wheel slip being all too common an occurrence.  The slow top speed though is, I think okay as it appears quite prototypical.

I agree,  I find a lot of RTR models to be overgeared, which messes up the slow-running and allows unrealistic speeds, though things are a lot better than they were 30 or more years ago!  Looking at layouts at exhibitions and in videos, it is also fairly obvious to me that many modellers' impression of realistic speeds allows much faster running than it should. 

 

As a rough guide, for steam-outline, most locos emit four exhaust 'chuffs' per driving wheel revolution, and 3-cylinder types emit six.  The Southern's Lord Nelson class put out eight chuffs per driving wheel revolution, but that was a one off.   So, with a bit of observation of preserved steam or video of 'real' steam, one can gain a fairly accurate idea of how fast locos were going, and how they accellerated from rest.  Bear in mind that locos with smaller driving wheels had lower top speeds but would accellerate more quickly from rest, and that not all video recorded the locomotive sound in sync with the image (tv & film are particularly guilty of this).

 

The Lyme Regis branch, which was where the last 3 Adams Radials worked for many years, did not require high speeds and the Ox model's top speed is probably adequate.  But these locos were originally used by the LSWR for fast outer suburban work out of Waterloo, and could probably be expected to run up to 50 or so mph; not sure the Ox will manage that with 20-odd 4/6-wheelers.  But how many modellers have layouts on which a Radial will be realistically asked to belt through a station at it's top speed anyway; even in their LSWR days they worked traffic that stopped everywhere!

 

But even the Hornby version probably performs more smoothy at low speeds than the typical 1980s offering with traction tyres and the pathetic combiniation of a feeble pancake motor driving through friction-lossy plastic spur gears; these were impossible to control below about a scale 30mph, make that 40 for express locos with big driving wheels.  Real trains may stop quite abruptly and accellerate rapidly (and not just modern traction; a 56xx with 5 bogies on would be up to 50mph from a standing start before the last coach had cleared the platform, even uphill, and J69 accelleration was legendary), but they do not (unless something has gone badly wrong) do brick wall stops or stabbed rat starts; stopping and starting needs to be smooth and not sudden.

 

OTOH. there is no need for snail-racing either.  For some reason this seems to be a feature of 0 gauge layouts at shows.  On the real railway, there is (believe or not) a timetable to be kept, and everybody wants to get the job done and go home/up the pub as quickly as they can, so long as they don't kill anyone or break anything in the process.  If your train is passenger/NPCCS/fully fitted, get up to line speed or fastest wagon speed as quickly as is decent; that's what happens in real life!  Part-fitted or loose-coupled goods needs to be slower and accellerate/brake more gently, softly softly catchee monkey is the name of the game here, and a dark art it was, too!  Unfitted loose-coupled trains (the bulk of mineral traffic until the late 60s) are limited to 25mph and timed for 20, so that the driver has a little in hand to keep 60-odd couplings taut o'er hill and dale, so taking it easy with these is realistic.  But it still isn't an excuse for snail-racing.  Propelling stock into goods sheds is, and spotting wagons under loaders or on weighbridges, but not much eles; get on with it!

[GWR-fan]

I like the slow speed but it takes 12 volts full throttle to get it there.  It will manage two bogie coaches or around ten wagons withut slowing down in the forward direction.  A lot slower in reverse.

[GWR-fan]

This is a video by "OOBill" where he investigates the slow running of the model.  After thoroughly cleaning the thick grease from the drive the model ran much better, even hauling three bogie coaches with apparent ease.  The mechanism seems rather simple so it looks like I have a maintenance repair job to do.  If no improvement then I will check "Sam's Trains" video where he replaced the motor.