Side Rod offset
- Hi Guys:
Having built several Steam Engines , one of which is a live "O" gauge ,
I think a bit of steam info. might be helpful to understand why the side
rods are in different positions on each side of the Loco . The cylinders
on each side are individual Double action ( push/pull ) engines , and
are subject to being stopped with side rods on dead center and will not
start again until moved off dead center . The solution to this problem
on two cylinder ( two engine ) Loco's is to have their centers exactly
90 degrees apart on the axle that connects them together . This makes it
impossible for both engines to be stopped on dead center and one side or
the other will always be in position to start the Loco . Any multiple
cylinder Steam Engine therefore does not need or require a flywheel and
should explain why a Loco can start into motion when the wheels ( in
effect the so-called fly wheels ) are not previously spinning . The
weights on the wheels are counterbalances to the weight of the side rods
and valve rods and any other attachments to that particular wheel . In
the case of our little jewels , the side rods do not drive but , are
driven by a gear train and because of the tolerances required , a
perfect 90 degree orientation is impossible . Marklin has solved the
problem by slotting the end holes in the side rods and any "thumping"
you get is because you are off one gear tooth on one end or the other
and the pins are hitting the end of the slot before they go over center
. I hope I didn't make this too technical but live steam info is dying
out along with us dinosaurs who lived with it . I may add that my 88641
was a mild "thumper" right out of the box and one gear tooth correction
made it a totally quiet performer .
Happy "Z"ing Nel
- Hi Nel,
Terrific explanation. Your observation that the steamer was 1 gear
tooth out of synch right out of the box doesn't surprise me one bit.
While touring the Märklin factory last year I was amazed to see the
so-called test run area. The locos were placed on a test track and
run at FULL speed around the track, first forward then
backward...then placed in the box for shipment! No wonder the
thumpers manage to get through their QA. Too bad since I've had
nothing but trouble with Märklin steamers and had to fine tune them
myself. This is no way to build confidence in a product.
It almost makes one wonder what Märklin really thinks about their Z
line. Collectors don't need good running locos, do they?