Newer 4/6/2 steam locos loco drive with fixed rear bogie / dolly

[Robert -348404]

Hi all I have a mallard and tornado with the fixed rear bogie I assume this was for cost cutting I find that I have derailments of the front bogies on these at times and it seems like they seem to pull a wheelie and it lifts the front end up as the fixed rear bogie doesn’t seem to give much support at the back and as a consequence the front bogies derail mainly on a bend or points is there a cure as the only thing I can think of is put extra nose weight the front of the locos

also they both don’t seem very fast on full speed and I’ve not done anything to speed programming they are both dcc

[ColinB]

I must admit the only disadvantage I have noticed of the fixed pony truck is it messed up my idea for operating a relay to set frog polarity with the blade of the point. The issue of derailing with the front bogie is either there isn't enough weight on it or the back to back wheel alignment is wrong. I did also notice that sometimes it is due to there not being enough travel (up and down movement) on the bogie itself. On the latest Coronation Duchess I ordered on the club I found it derailed easily. I compared with my other Duchess locos and found they have used a shorter shouldered screw to hold the front bogie to its bracket, meaning on my layout it derailed all the time on one section of track. Replaced the screw with a longer one and the problem solved.

[508006]

I must admit that I too have found the fixed rear part on the latest steam locos to be a complete pain.

I recently drilled out the chassis around tis rear fixed pony section ( cab end ) on a P2 chassis so that I could fit flanged wheels to the loco without it shorting out the power.

Tge flanged wheels worked great on straight track but on curved track they would derail the loco no matter which direction it was running.

I have been investigating the possibilities of finding a way to remove the part concerned and convert it into a swivelling rear pony just like the locos used to be.

On older super detail locos which had a plastic representation of the cartazzi truck on LNER locos, I have been able to successfully convert them into swivelling wheel sets with a bit of cutting, fabrication, filing, test fit, more filing and final fitting once correct, however, figuring out how to do this on thd Hornby Tornado and P2 has so far eluded me but 1 way or another, I will figure it out unless someone beats me to it.

[ntpntpntp]

Hi all I have a mallard and tornado with the fixed rear bogie I assume this was for cost cutting

Done so that it matches the prototypes, I believe. The '-2' part of LNER pacifics is not a separate moveable pony truck.

 

 

Yup, the Cartazzi axle has sideplay but the axleboxes are part of the main frame.

The trouble is we've got used to the toy train design of pivoted rear truck to get round unrealistic tight curves.

My TT:120 A4 has the flangeless rear wheels. No problem other than they are obviously not over the rails and look odd on the tighter radii, but then to be honest the whole loco looks odd on tight bends :)

 

 

[atom3624]

The wider-than-standard cartazzi with the floating flanged wheels on Bachmann locomotives seem to work well.

I often find the fixed Hornby ones too low and have to lift up the axles of the non-flanged wheels to stop them getting trapped on curves.

Al.

[ColinB]

I think on one Bachmann A4 I have the rear wheels move from side to side and are flanged. I notice though now Bachmann have gone with the flangeless option.

[508006]

I have the Bachmann A1 Tornado and another A1 which is numbered and named as 60153 Flamboyant.

Both of them are fitted with flanged wheels under the cab but unlike the hornby version of the Peppercorn A1 where the wheels under the cab are fixed in place, the Bachmann version has a slot which allows the assembly holding the wheels can move sideways as the loco goes round curved track and when running in reverse the Bachmann locos does not derail compared to constant derailments of the hornby version.

[Tony57]

Hi

I have a question. Did the model makers in years gone by get it right with movable rear bogies and today's makers got it wrong? or are today's right and yesteryears wrong?

The reason I am asking that question I just again watched the video recording of the lifting of 35011 Steam Navigation's boiler and the removal of the trailing truck, the rear trailing truck has a pivot hole at the front end of its frame and at the rear end of the main frames has pivot spike. I understand there is a side to side control mechanism on the rear trailing truck, which helps guide the loco around bends. So that would indicate that on Merchant Navies the trailing truck could pivot. I wonder how many other locos rear bogie / truck pivot in real life? Do today's models need to reflect this?

[Fazy]

The SR light and heavy Pacific’s had a pony truck which dose swivel to some degree.

has dose the 2 ex-LMS,BR Ivatt Princess Coronations

The LMS and the LNER approached the trailing wheel problem differently. The LMS and LNER used a subframe to support the cab and part of the firebox. These do NOT move! The wheel sets in side do however the LNER used the Carrtazzi the LMS used a Bissel truck. So the model are now closer to the real thing. What makes it look wrong is quite simple the toy curves on the layout.

[508006]

Another thing that does not help in terms of models with fixed rear pony wheels is that some turnouts still have tight radii.

1 example is the peco 3 way turnout, when going straight on, my P2 & Peppercorn A1 will run over it no problem but when going to the left or right the rear wheels derail no matter which direction they run over them.

I have also discovered that the radii for the curved directions on a 3 way are the same as on thd peco medium radius turnouts which has had me toying with the idea of trying to put together a long radius left and long radius right hand turnout in an attempt to build a long radius 3 way which I think is needed in the track range.

Fixed rear pony trucks are great if a layout is the size of pete watermans making tracks layouts which would have very generous curved sections which are very similar to those on the real railway but in model form, there are still plenty of us who do not have massive areas to build layouts with these very generous curved sections so in that respect I get it but for those of us who do not have massive areas to build in, we need models that can still negotiate curved track but at the same time not end up looking like a dogs back legs.

[Potterton]

The scenic section of my layout has quite generous radii on the curves, (36" and above), but in the hidden fiddle yard in order to gain siding length I resorted to using second radius curved track. Unfortunately in my haste and admitted carelessness I used a number of sections of first radius curves. Fortunately, I have found that this has not presented any problems of any sort to any of my locomotives or rolling stock including a 9F, a 28XX and a Hornby A4, the latter with fixed pony truck wheels. All run through with no suggestion of derailing at all speeds. Aesthetically though they do not look great doing it, but as I say, it is only in the hidden sidings.

[atom3624]

My Bachmann pacifics with the floating flanged wheels generally have no problems negotiating the 2nd radius standard points / turnouts - I've 5 of them. (4x A1's and an A2).

Al.