P D Marsh Sentinel shunter

[Dorsetmike]

Just bought one of these on that auction site, should arrive tomorrow or Monday.

It calls for a Farish motor bogie which seem to be a bit scarce now, is there a suitable alternative among the many far east ones also on that auction site?

What Wheel diameter and spacing should I be looking for?

[EtchedPixels]

The Marsh sentinel is geometrically bogus in various ways to fit the motor bogie. You can cut it down to the right length and remove the extra block for the motor and stuff one of several of the small Japanese chassis under it, although they are 4.5v so usually want a resistor adding. TU-7T is one choice, although something slightly longer may be better.

The general arrangement was 2'6" wheels and a 7ft wheelbase

Alan

[thebrighton]

I used the chassis from one of these for mine and IIRC the wheels line up with the axle boxes. It also means you can get rid of the lump forward of the cab where the Farish chassis protrudes.

http://www.vectis.co.uk/AuctionImages/444/419_l.jpg

Gareth

[Dorsetmike]

I found an entry in Wiki for the Y10 and S&DJR ones which quoted 3'2" diameter and 6' spacing. I did note that some of the chassis were 12V others 4.5V, a resistor should not be a problem, find the current drawn at 4.5V using 3 x AA cells, then apply ohms law for the resistor to dro 7.5V and make sure it's sufficient wattage to not cook the body shell!.

Probably use a slightly higher value resistor than the calculation calls for, dont really need a 60MPH Sentinel!

[thebrighton]

Here are some photos of my Sentinel. Hopefully the link will work as the photos are on the N Yahoo group.

http://xa.yimg.com/kq/groups/1038102/sn/1744717224/name/n_a
http://xa.yimg.com/kq/groups/1038102/sn/3546280/name/n_a

Gareth

[EtchedPixels]

I found an entry in Wiki for the Y10 and S&DJR ones which quoted 3'2" diameter and 6' spacing.

The Y10 is a different beast - the experimental double cab sentinel. The S&D sentinels likewise are very different beasties to the kit.

The kit is vaguely accurate (ignoring the massive deliberate dimensional errors) for the LNER units and for the brief experimental GWR one. There are differences however. The early LNER needs the grilles filling and the bottom of the buffer beams angling. The early GWR needs the grilles filling. The roof also varies somewhat between units. The later LNER ones it's pretty close to.

It's not a lot of use for modelling S&D or Y10 units.

Alan

[Dorsetmike]

Sounds like a rule 1 situation os developing! Shed pilot???

[CarriageShed]

I also had my eye on the P&D Marsh kit, but once I realised that it looked nothing much like the S&D version, I lost interest.

Good luck with the chassis production part, Mike. I'm really looking forward to seeing what you come up with.

Peter

[Dorsetmike]

Opened the pack yesterday and did some measuring then trawled fleabay for something that might be made to fit, the Japanese ones have wheels about the right size but spacing is either way to short or way too long, I'm wondering if I can shorten this one

http://www.ebay.com/itm/Super-Mini-Size-Motorized-Chassis-TU-TMC100-Tsugawa-Yokou-N-scale-/121177837186?pt=Model_RR_Trains&hash=item1c36c30e82

Wonder if it's 2 wheels or 4 wheels driven

Or lengthen this one

http://www.ebay.com/itm/Super-Mini-Size-Motorized-Chassis-TU-7T-N-scale-/121169458884?pt=Model_RR_Trains&hash=item1c364336c4

Says only 2 wheels driven  so may have possibilities.

If anyone has used either could they please comment.

[EtchedPixels]

The TMC100 can be shortened. See

http://www.rmweb.co.uk/community/index.php?/blog/79/entry-12323-tsugawa-tu-tmc100but-not-how-the-manufacturer-intended/

[Dorsetmike]

That looks doable Alan, thanks,  the axles on the Sentinel look to be spaced about 17mm, how close should that chassis get to that?

[EtchedPixels]

The Sentinel should be 14mm (7ft) but like the way the body is stretched (wants about 4mm removing) the side frames are stretched to 17mm

The shortened chassis comes out at 15.5mm centres

[Dorsetmike]

In the kit is the extra length in one area, or spread, in other words could some be removed from the cab or the other end, or a bit from bothe ends, or just accept it as is?

[EtchedPixels]

If I remember correctly for the body its just about 4mm added in one place.

[Dorsetmike]

The TMC100 chassis is barely 2mm short of the Sentinel body, so for my first one I'm leaving the body as is except for removing the bit that covers part of the Farish bogie and filling the resultant gap in the tank top and made a new spectacle plate from brass.

As the wheels have been moved in from the end, the cogs that were at the end I removed and used the space for fixing screws

[smg id=7323]

I made a few errors  on this one so have a second one awaiting another chassis. biggest boob was  putting the roof on wrong way round and as it was soldered on it didn't wanna come off, so I filed off the roof vent, drilled a hole for ther chimney and fabricated a new vent.

The resistor I fitted to drop the voltage to the motor to 4.5V was a 120 ohm 1 watt, seems to run happily enough with that. The motor was also connected to run in the opposite direction to all my other locos, so rewired it when fitting the resistor.

On the next one I'll shorten the body to fit the chassis - about 2mm - it'll still be a little long.

Now on the horizon the Sentinel-Camell steam railcar that ran on the Devils Dyke line SR 1933-ish. still very much in the thought stage! The Langley sentinel railcar kit looks nothing like it, not only "sreamlined" ends but windows are different, could be fun, the Langley one has been built on a Tomytec chassis, I've got a set of drawings promised so just see how it looks with them to hand. Pity the Drummond railcars didn't survive, just how far can one stretch rule 1?