How do I get the pulley off the dynamo?
|N.B. You really only need to do
this if you are swapping pulleys between dynamos or need
access to the front bearing. Brushes can be inspected /
changed without removing the pulley and front plate.
The nut has a standard thread i.e.
undoes in an anti-clockwise direction as you face the dynamo. It
is done up to a high torque but a compressed air impact gun
undoes the nut easily as long as you can hold the pulley
firmly enough to prevent it turning without
damaging it. For difficult cases make use of the two
threaded holes as shown opposite (they are M8 thread).
The outer pair of bolts are just packing.
If the pulley has recently been
removed it will slide off the shaft once the nut and
washer have been removed. The chances are though that it
will be stuck solid and you will need to use the method
||Thread two M8
bolts into the holes in the pulley until they meet the end
plate. Tighten each a a bit in turn and they will slowly
move the pulley forward off the shaft. Once the mating
surfaces of the pulley and shaft have been cleaned and
greased the pulley will simply slide on and off the
The woodruff (half
moon) key may stay in the shaft when the pulley is
removed or may need tapping out but be careful not to
On a Marchal dynamo the endplate
is in two parts and includes a bearing cover secured by
six recessed bolts with allen key heads. To remove the
whole plate is a matter of undoing the six bolts round
the outside, then using two of these bolts in the
threaded holes to act as a 'puller'. The procedure is
the same as shown below for the rear cover plate.
How do I get to the brushes?
|To examine or change the brushes
the rear endplate must be removed. Note the use of a
piece of copper tube to protect the electrical socket)
Once the six retaining bolts have
been removed two of them are used in the spare threaded
holes as shown to pull the end plate out. It is a tight
fit due to the rubber seal (clearly visible in the photo
far right). On a Paris Rhone dynamo there are no
threaded holes for this but the end plate protrudes
beyond the main casing and can be tapped off a bit at a
time working round the circumference.
Brushes on a Marchal type dynamo
||The end plate cannot be
completely removed until two of the electrical screws
that connect the brush assembly to cables from the main
body are undone. These also secure the wires from two of
the brushes so make a careful note of where everything
goes! The Marchal dynamo has four brushes with bevelled
ends as they are mounted off-centre. Click the image
to enlarge /
Cliquez pour agrandir l'image
The Marchal type dynamo I have
dismantled for the photos is from a rebuilt engine
unused apart from the factory running in process to
achieve the final 'fiche de
rodage' certificate. I am about to send the brushes
away to have a duplicate set made. Having done so and
assuming the quality is ok the company will then be able
to produce sets of brushes for M201 owners. Watch this
The Paris Rhone dynamo has a
different brush assembly and brushes. I intend to
dismantle one in the next few days to both photograph
and to send the brushes away to get a duplicate set
made. So again, watch this space.
Before reassembling, clean and grease the
rubber dust / water seal. Having four brushes, the Marchal type
dynamo is quite tricky to reassemble and I don't recommend
attempting this when you are tired / not in a good mood.
Basically, pushing back all four brushes to allow them
onto the commutator and keeping everything in place while you
reconnect the wires that connect to two of them (if you have
disconnected these) is all but impossible unless you make
up four pins to hold the brushes back until reassembly is almost
complete (see photo opposite).
The pins I used were made from coat hanger
wire and worked well but with the benefit of hindsight it would
have been better to have completed the loop at the end of each
and tied a piece of thread to each to make removal easier. With
the pins in place to hold the brushes back it is possible to reconnect the wires
to two of the brushes. Getting the tags on the wires to line up
with the threaded hole on the brush assembly so that the screw
can be inserted is a challenge that can be made easier by using
a nail to line them all up. A finger and thumb can then be used
to pinch them together in place before removing the nail and
inserting the screw. (see photo below)
Once the wires have been reconnected to two
of the brush assemblies the end plate can be eased towards the
body checking that the brushes do not catch on the commutator.
With the brushes in place over the commutator and a small gap left between the end plate and the
body, remove each of the pins allowing the brushes to make
contact with the commutator. Make sure the bolt holes line up
before tapping the endplate in working round the edge to keep it
square. When it is home far enough the bolts can be inserted and
used to finish the task but again they need tightening
equally working round the edge to move the plate in squarely and
a bit at a time.
The dynamo worked fine after its dismantling
ordeal though having four brushes certainly made the reassembly
more challenging. With only two brushes the Paris Rhone dynamo
is rather easier to dismantle and reassemble to inspect the