Dingham Electromagnet for Remote
The instructions for Dingham Electromagnets are included here to give
prospective purchasers comprehensive information on the magnets and hints on
positioning, fitting and operating them.
The instructions below are not an exact replication of the printed
instructions. In particular, the quality of the illustrations is inferior to the
printed version. However,by clicking on this
link, you can open a pdf version of the instructions and print it out for
yourself. You will need a pdf reader installed on your computer. If you do not
already have a pdf reader you can download and install Adobe®
Reader by going to
are produced by modifying industrial quality solenoids. The modification
consists of making provision for an extended pole piece (an M5 x 60mm bolt), long enough to reach
through a 12.5mm (1/2in) thick baseboard to the level of the sleeper tops of
electromagnets are of higher resistance
than other electromagnets offered by the model railway trade. This means they
take a current of less than 1.5A when connected to the recommended 12V DC supply.
(a) Solenoid body with central 5mm diameter hole for pole piece.
(b) Pole piece (an M5 x 60mm hex-head bolt).
(c) Three M5 washers.
Supply – The Dingham electromagnets should be operated on a nominal
12V DC supply (usually obtained by rectification of 16V AC). Switching MUST be
via a non-locking push-to-make switch (e.g. All Components Code SMT6 or Maplin
Code FH59P) or a non-locking biased-to-off toggle switch (e.g. All Components
SPB1 series or Maplin Code FH03D). The electromagnets will NOT operate on AC.
the Magnets on the Layout – The
importance of positioning the magnets cannot be over-emphasised. It requires
careful thought and experimentation if the most railwaylike (and enjoyable)
operation is to be obtained. The positioning of magnets on Lofthouse, the
Skipton & District Railway Society’s O Gauge exhibition layout, will be
used as an example.
All passenger trains enter Lofthouse
from the left in the diagram alongside and are reversed. Magnet 2 is positioned
to release the loco from an incoming train of three 4-wheel coaches, perhaps
with a tail load (horsebox, etc). The train is stopped with the coupler over
Magnet 2 and the loco is reversed about 3mm, buffering up to the train. Magnet 2
is energised and the loco is released.
Magnet 1 is
positioned so that the rear coupler on the rake of three coaches is directly
over it when the front coupler is over Magnet 2. Thus, if a tail load is
present, the loco can run round, buffer up to the tail load and move it forwards
about 3mm to slacken the coupling between the coaches and the tail load. Magnet
1 is then energised to uncouple the trailing load from the coaches and the tail
load can be shunted into the yard. The three coaches are not moved during
detachment of the loco or the tail load.
running left-to-right through Lofthouse use the loop road. They stop at Lofthouse
to have the brake van detached and a banker attached to the rear for the steep
climb to the right of Lofthouse station. Trains are stopped with the
brake van front coupler over Magnet 3. The banking loco, stabled in the short
spur next to the home signal (A) then moves forward and pushes the brake van
forwards about 3mm to slacken the coupling between the van and the train. Magnet
3 is then energised to uncouple the brake van, which is drawn backwards from the
train. The train then moves forwards to clear the turnout leading to the yard
and the banker shunts the van into the yard, uncoupling the van as it passes
over Magnet 3. The banker is then attached to the rear of the train.
Shunting the yard
could be done using Magnet 3 only, but Magnets 5 and 6 are provided to allow
more realistic operation (i.e. wagons do not have to be withdrawn as far as
Magnet 3 if this would be unnecessary in reality).
running right-to-left through Lofthouse use the platform road and are
double-headed for braking purposes on the steep bank leading down to Lofthouse.
In Lofthouse station, the pilot engine is detached and the train picks up
a brake van from the yard before departing leftwards. The incoming train is
stopped just short of the starting signal (B) with the coupler between pilot
engine and train engine over Magnet 1. A section break coincides with the
position of Magnet 1. The power to the train engine is switched off, the pilot
engine reverses about 3mm to slacken the coupling. Magnet 1 is energised and the
pilot engine is released and parked in the spur. The train then pulls forwards
and reverses onto a brake van in the yard, couples up and departs.
Magnet 4, not
mentioned so far, is hardly used and is probably unnecessary.
illustrates how careful positioning of magnets can play an important role in
realistic operation. For example, Magnet 1 must be positioned just over a
loco’s length in rear of starter signal B, to allow uncoupling of the pilot
engine from right-to-left goods trains. This in turn sets the position of Magnet
2, which must be three 4-wheel coach lengths to the right of Magnet 1 to allow
the release of locos from incoming passenger trains and detachment of tail loads
without moving the passenger coaches.
Magnets to the Layout – The magnets are fitted to the layout as
shown in diagrams 1 and 2 below. The pole-piece/bolt may be secured in the
baseboard either by drilling a 4.5mm hole and self-tapping the M5 bolt into this
or by glueing the bolt into a 5mm hole. If tapping the bolt into the baseboard,
use a driver fitted with an 8mm hex socket.
falls off very rapidly with increasing distance from the magnet. In fitting
magnets to the layout, the aims should be to have (a) the coil of the magnet and
(b) the pole piece as close to the coupler as possible. ON NO ACCOUNT
SHOULD THE TOP OF THE SUPPLIED POLE PIECE EXTENSION BE BELOW THE TOPS OF THE SLEEPERS and if it can be arranged to be a little higher, and disguised, so much
Diagrams 1 and 2 show how the magnets should be fitted to the
baseboards. After deciding the set-up, the pole-piece should be
shortened to suit before the magnets are fitted to the
layout. Do not be tempted to use the full length bolt. It must not project more
than 20mm above the two upper washers.
If recesses have to be made in thick baseboards before
scenic work has started, they may be made with a chisel or with a spade-type
drill (diagram 3). However, after scenic work has been done then great care must
be taken and the only type of drill that can be recommended is a type intended
for drilling recesses in kitchen cabinet doors to take hinges (see diagram 4).
These bits produce a flat-bottomed hole 35mm in diameter and are easily
controllable, so may be used with confidence on scenic boards.
– If the Dingham system of electromagnets and autocouplers appears
not to work perfectly, check the following –
12V DC is actually reaching the electromagnet, i.e. there is no serious
voltage drop between the supply and the magnet. The most likely cause of
unacceptable voltage drop is a switch with carbon deposits on the contacts,
caused by arcing.
The top of the electromagnet pole piece is at least level with the
tops of the sleepers.
The droppers on the couplers are not too short (they should barely clear the
rail top) and are free to swing longitudinally.
There is no stiffness in the couplers. The loops and latches should fall
readily under their own weight.
There are no obstructions such as vacuum pipes preventing the couplers
Buffer and coupler lengths are correctly adjusted (see 7mm
Autocoupler Instructions or 4mm
Autocoupler Instructions) and uncoupling is not prevented by the loop pushing against
the back of the slot in the opposing hook (happens on straight track if buffers
are too short) or by catching under the tip of the hook (happens on curves if
buffers are too long).
[ Back to Top ]