All --
Regarding John Degnan's questions:
1. How much clearance is there between the bridge and rolling models on the
sides and top of your widest/tallest models?
Clear width is 2-7/16", or 13 scale feet -- equal to the standard prototype
lateral distance between multiple tracks on mid-20th-century east coast
railroads. Clear height above code 100 railhead is 3" (16 scale feet) -- the
absolute minimum on older east coast railroads. No piggy-back traffic here!
2. If the bridge is indeed "unmodified", how was the S scale track secured to
it?
Real high tech -- a small rubber band, grabbing the opposite ends of one
flextrack tie in the center of the movable span, wrapped around the underside
of the support girders. The flextrack is connected to fixed hand-laid rail on
both ends of the bridge with standard rail jooiners. These can be pushed along
the rails (off the joints) so the entire bridge can be removed -- which I still
have to do to paint it. I built the bridge to actually work if I wanted it to,
but the track through it is continuous -- and removable. The motor is not
powered. But I did try it out before installation, and it works well. The DC
motor can be reversed, and in fact the kit comes with a diode matrix that
reverses the direction of the bridge motor. However, the limit switches in the
kit are really hokey, so I did away with the matrix and the limit switches. If
I ever power it I will use micro switches to stop the motor and a simple dpdt
switch plus diodes to reverse it.
I did make one minor modification that I had forgotten -- Merely cosmetic.
Although the counterweight originally hung no lower than the 3" vertical
clearance, I thought it looked too low. So I later shortened the counterweight
by 1/2". If one were to actually power the bridge, weight (like bird shot)
would be required in the hollow counterweight.
3. Since the bridge was designed for HO models, does it sag any due to the
heavier weight of S scale locos?
The bridge is large -- 28 inches long not including the walking beam and
counterweight -- i.e., from the far end of the movable span to the entry gate
on the other end. The movable span itself is 22" long from hinge to tip. I
made no mods to accommodate S scale loco weight, and the bridge does not sag.
The loco I use on this branch is the 0-8-0 in the photo. This is a zamac and
brass loco, fairly heavy.
Dick Karnes
====================
PS -- I just received an Atlas O scale through truss bridge kit from Des
Plaines Hobbies. This bridge will have its O scale track removed (and sold on
eBay), replaced instead with my three-track line over the lift-out to my layout
room. Its 44" length is just right for my 4-foot doorway, and its 8" vertical
clearance allows catenary to be strung right through it.
For those who want to know how I can squeeze catenary into the Walthers HO
bridge -- Not gonna happen. The Port Hudson brance is non-electrified -- steam
and diesel only.
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