Cornerstone BASCULE BRIDGE User manual

HO Structure Kit
BASCULE BRIDGE
933-3070
© 2016 Wm. K. Walthers, Inc., Milwaukee, WI 53218 waltherscornerstone.com I-933-3070 Printed In China
Thanks for purchasing this Cornerstone® kit. Please read these instructions and study the drawings before starting
construction. All parts are styrene, so use compatible glue and paint to finish your model. As part of the Cornerstone
Engineered Bridge System, walthers.com/bridgesystem, your new model can easily be used with other Corner-
stone bridges and accessories to create a custom structure for your railroad. PLEASE NOTE: your new bridge is
designed as a working model. The gears in the drive mechanism are made of Delrin® plastic and should be lubri-
cated with a light, plastic-compatible grease before operation.
Rivers have always challenged railroad bridge builders, especially where the waterway is used for commercial
shipping. While pleasure boats require very little clearance, ocean-going freighters or large naval vessels must also
be able to pass safely. In congested urban areas, the best choice for the job is a Bascule bridge.
Fixed at one end to open and close like a jackknife, the basic idea dates back centuries, a common example being
drawbridges over moats protecting medieval castles. For railroads, the design has many advantages. Smaller and
simpler, they have fewer moving parts than other movable bridges, so they’re cheaper to build and maintain. Their
greatest advantage however is that they can be partially raised to quickly clear small vessels, then closed, making
them an ideal choice for busy rail lines.
The actual lifting work is done by a large counterweight, with help from a heavy-duty electric motor and gear drive
to overcome its inertia. As the balance point is reached, the motor shuts off and gravity takes over, raising the
bridge.
Because approaching vessels have the right-of-way, the bridge must be manned 24 hours a day; where a channel
is closed during winter months, the bridge is left in the down position. So that the bridge tender has a clear view of
the waterway and the railroad, a crow’s nest is mounted at the fixed end. Today, he or she is in radio contact with
passing trains, as well as approaching vessels since advance notice is required to coordinate safe movements.
Before centralized traffic control, an interlocking tower was an integral part of the bridge, where the operator
controlled signals regulating movement of trains across the structure. Railroads preferred to build single-track
bridges, and it was easier to funnel a double-track mainline into a single track, with additional turnouts and signals
on each side.
For added safety, all signals interlocked with the lifting mechanism so a signal to proceed could only be displayed
when the bridge was closed. While the lowered counterweight would effectively stop an approaching train on that
side, some roads also installed derails (special track switches that would actually derail the train) or “smash boards”
(similar to a semaphore blade that hung over the tracks) if the engineer failed to stop.
While the majority of Bascule bridges were stand-alone installations, if conditions required approaches standard
bridges were used. The Bascule Bridge was installed over the deepest part of the channel, where the largest
vessels would pass.
Due to their heavy steel construction and regular maintenance, many of these bridges have provided decades of
service and remain in daily operation. In some areas where shipping traffic was diverted or eliminated, moving
bridges are no longer needed. But since they are expensive to replace and are in useable condition, the existing
Bascule Bridge was simply left in place.
Based on a Northern Pacific bridge crossing the Duwamish River in Seattle, Washington, and still in use by BNSF,
similar Bascule Bridges can still be found on all types of railroads today. To prevent derailments or severe damage
to the structure, they’re fitted with special track and guardrails, which can easily be added to your model with
Walthers Code 83 Bridge Track with Separate Approach Ends (#948-886, sold separately). To simplify installation
in new or existing scenery, Single-Track Railroad Bridge Concrete Abutments (#933-4551) are available separately.
For more ideas and information on the Cornerstone Engineered Bridge System please visit
walthers.com/bridgesystem. For additional products to complete your scene, see your participating hobby dealer,
check out the latest Walthers Model Railroad Reference Book or visit us online at walthers.com.

1
Enlarged View
Lower
Abutement
Switch
Assembly
PLEASE NOTE: This model is designed
for use with Walthers Code 83 Bridge
Track with Separate Approach Ends
(#948-886, sold separately), which can
be installed during this step for easier
construction.
1) With the alignment tab along a straightedge (tabs point to the ends), make two Girders by gluing Short (6) and Long
(16) sections lengthwise as shown; set this assembly aside to dry completely. Glue notches in Girder assemblies to open-
ings in Cross Girders (6x 7). Continue assembly by gluing Right End Girder (8) to the pivot (right) end. Note the tab on
Left End Girder (#128) is at the bottom: complete assembly by gluing to left end as shown; set aside to dry.
2) Glue Left (3 & 5, 13 &15) and Right Side Girder Halves (2 & 4, 12 & 14) together. PLEASE
NOTE: Glue Splice Plates (2x 20; one per side) to lower edge of each pair of sides as shown,
making sure they are all the way up and in the slot so they will not interfere with bottom bracing.
Set this assembly aside to dry.
3) Glue Top Girder Halves (10, 18) together lengthwise as shown. Insert the four
Latticework sections (one each #101, 102) to form an X-shape; the joint will
need to be fitted to accommodate the angle. Glue the Single Latticework
Sections (3x 100) to the Top Girder assembly as shown. Align the ends of the
X-shaped Latticework (assembled from parts #101 & 102) and adjust as needed
so parts fit square and snug, and apply a little glue where parts meet.
4) Align ends of Cross Girder assembly with right and
left Side Girder assemblies and glue in place. Fit and
glue Top Girder assembly in position. Glue Portals
(9, 17) to ends of Side Girders. Glue End Caps (4x
19) to Side Girders as shown. Glue Bottom Bracing
(1, 11) to underside of Girder assembly.
5) PLEASE NOTE: For a nonworking model only,
glue Bridge Shoes (2x 200) to pins on Side Girders
as shown. For a working model, you’ll need to
assemble the Lower Abutment Switch for later instal-
lation atop a bridge abutment
or pier (both sold separately):
final installation and
127
128
97
alignment are covered
in Walking Beam
Support Assembly step
9. The Switch Holders
(Right 126 and Left
127) are mirror images;
be sure the extended
“wings” are glued to the
top of the Abutment
Plate (21) as shown. Insert the Micro Switch
between the Holders, along with the Filler
Piece (97); adjust the fit as needed and secure
in place with 16mm Long Machine Screws and
Nuts as shown. Set aside for final assembly
steps.
200
200

2
Diode Cabin Micro Switch
Diode
Motor
Abutment Micro Switch
to power source
6 volts DC
DPDT Reversing Switch
Cabin & Drive Subassembly
Drive and Wiring Assembly Diagram
6) Note the correct placement of all components on the motor wiring diagram below; the light
colored area on each diode indicates its proper orientation. We suggest using a double-pole,
double-throw reversing switch (sold separately) to turn the motor on and off. Use a DC power
supply (sold separately) that can be adjusted to about 6 volts.
7) Using the metal rod provided, cut drive shafts to these lengths and lightly
bevel the ends:
2x #114: 3.8" (99mm) each
1x #117: 0.9" (25mm)
6x #119: 0.3" (10mm) each
8) On the end opposite the wires, press a Worm Gear (115) on the
Motor (113) shaft. PLEASE NOTE: Cut the other end of the shaft
so it’s about 1mm long; if using a power tool and cutting disk, wear
proper safety gear and work carefully; do not overheat the shaft!
9) With the Cabin Micro Switch all the way at the ends of the slots,
attach the Switch to the Platform (125) with the 16mm Long
Screws and Nuts. Cut two pieces of wire about 4" (10.1cm) long
and a single piece 2" (5cm) long to prewire the Cabin; solder wires
to Motor, and solder wires and diodes to Cabin Micro Switch as
shown on the wiring diagram.
10) Assemble Short Drive Shaft (117) as shown with
Large (115) and Small (116) Gears inset 0.09"
(2.5mm) from each end.
11) PLEASE NOTE: Small Gears (2x
116) as shown are installed in a later
step. Press Large Gear (118) on to
Shaft (114), 0.9" (25mm) from the end;
Slide Shaft through small holes in Right
(91) and Left (92) Motor
Mounts and End Wall
(35); the Large Gear will
rest near the Right Motor
Mount. Slide Shaft
through small holes on
opposite End Wall (91).
12) Slide Left (93) and Right (94) Short Shaft Supports onto ends of Short Shaft assembly as
shown. Using the pins to align parts, glue Shaft Supports into openings on Right Motor Mount
(91). Note the raised ridge on the Floor; align slots on inside of Right Cabin Wall (34) with
edges of Short Shaft Supports and raised ridge on Floor and glue in place.
13) Glue Glass (2x 38) to inside of Front Cabin Wall (37). Using raised ridges on Floor (33)
to align parts, glue Front, Left (35) and Rear (36) Cabin Walls to raised ridge on Floor and at
inside edges where parts meet. Roof Halves (2x 39) may be glued together where parts meet
in the center or left as separate parts. PLEASE NOTE: We suggest you set aside the front
and back Cabin Walls and Roof for later assembly after your Bridge is in place and the
moveable span is adjusted on your layout.

314) Slide Right Gearbox Half (47) over Motor shaft extending from right side of
Cabin. Press Small Gear (116) on the shaft, 0.07" (2mm) from the end. Slide Left
(46) and Right Gearbox Halves (47) over motor shafts extending from Cabin.
Press a Small Gear (2x 116; one on each end) on the shaft, 0.07" (2mm) from each
end.
15) Note the openings in the Girders (2x 31); glue Cross Girders (3x 96)
to openings and end as shown. Glue edges of Cross Girders to openings
in Inner Left and Right A-Frame, make sure parts are aligned and level,
and set aside to dry.
16) Before gluing the Outer Right (27) to Inner Right A-Frame (29), you
may wish to insert a length of wire or string to assist in pulling the motor
wires through this assembly in a later step. Glue parts together and set
aside to dry.
17) Glue Outer Left (28) to Inner Left A-Frame (30) as shown and set
aside to dry.
18) Glue Left and Right A-Frame assemblies to Cross Girders
and allow to dry.
19) Note the slots in Outer Right (27) and Outer Left A-Frame
(28); place - do not glue - Cabin Supports (4x 32) in these slots.
20) With the Cabin Supports loosely in place, spread the
A-frames, slide the Cabin assembly in place and check for
alignment. Thread the two wires through the Right Hand A-Frame
before gluing the Cabin Assembly and Bottom Braces (4x 32) in
place.
21) Glue Back Bracing (40) to
mounting points on Inner
A-Frames. Make sure they’re flat
and straight; set aside for later
assembly.
22) Glue Left (49, 50) and Right (51, 52) Racks
together; make sure parts are flat and straight and set
aside for later assembly.
Left
Right

4
Walking Beam & Weight Assembly
23) Using the pins to align parts, fit and glue Crisscross Latticework (104, 105) to bracing
on Upper Walking Beam Support (71). Using the pins to align parts, fit and glue Straight
Lattice (3x 103) to cross braces on Lower Walking Beam Support (70). Fit and glue Upper
and Lower Supports to each other, and glue to beam Sides (2x 72). Set assembly aside to
dry.
24) Fit and glue Latticework (106, 107, 108, 109, 110) to back of Bracing pieces (57, 58,
59). Glue Middle Bracing Halves (60, 61) together. Glue the Right (53, 54) and Left (55. 56)
Walking Beam Halves together and set aside to dry.
25) Check the alignment of the completed Bracing assem-
blies from Steps 1, 2 & 3 to Walking Beam Halves; when
satisfied with the fit, glue parts together as shown.
26) Using raised ridges to align parts, glue Counterweight
walls (62, 63, 64, 65 66, 67) at inside edges where parts
meet. PLEASE NOTE: Counterweight Top (68) and Hatch
Cover (69) are installed after you have added weight to
balance the bridge. Glue Counterweight to Walking Beam
assembly and allow to dry completely before proceeding.

5
DECALING
1. After cutting out the decal, dip in water for 10 seconds, remove and let stand for1 minute. Slide
decal onto surface, position and then blot off any excess water.
2. Lightly brush Micro Sol® on top. This will soften the decal allowing it to con-form to irregular
surfaces. DO NOT TOUCH DECAL while wet!
3. When the decal is thoroughly dry, check for any trapped air bubbles. Prick them with the point of
a small pin or hobby knife blade and apply more Micro Sol®.
22) PLEASE NOTE: To improve the fit of the metal pins (2x #119 cut in step 2), we suggest drilling a #48 hole in each Walking Beam Support mounting point and a #47 hole at each of the
four Walking Beam openings.
23) Insert metal pins (4x 119; two per assembly) to connect the A-frames to the bridge, and Walking Beam assembly to the top of the A-frames. Drill a #48 hole through the openings in
the racks, bridge and supports, and thread the Long Metal Rod (114) through these openings.
PLEASE NOTE: Before attaching the gear racks for final assembly, place the entire bridge on a flat, level surface so that all gears and gear racks will be in alignment.
24) Place - do not glue - Gears (4x 116; two per side) on shafts molded Inside Left (46) and Right (47) Gearbox Half (2x 46); make sure these mesh with the gear on the motor shaft and that the gears
turn easily on the gearbox half pins
25) Note the correct placement of the Gear Racks assembled in step 17 (right side shown); the open connection points face forward while the stops (raised round areas molded on the rack sides) are
at the rear towards the counterweight. Be sure the tab on the Left Gear Rack aligns with the Cabin Micro Switch arm. Place the Right and Left Gear Rack assemblies on the gearboxes.
26) Attach the Rack Ends to the Moveable Bridge Rod (114) with the End Cap Pins (2x 95).
27) Place the completed Rack assemblies with the teeth facing down on the gears; confirm that all gears on the gearboxes and racks align and fit freely. Carefully glue the edges of the Outside Gear
Box Halves (2x 48) to the edges of the Inside Gear Box Halves and let dry completely.
28) PLEASE NOTE: To facilitate raising and lowering the bridge, add approximately five ounces (141.7g) of weight (not included) such as BBs or sand inside the counterweight assembly; after the weight
is installed, glue Counterweight Top (68) and Hatch Cover (69) in place.
29) Apply a small amount of plastic-compatible grease (sold separately) to the Worm Gear on the motor shaft, and a drop of plastic-compatible oil (sold separately) to the other rotating parts.
30) Connect the motor wires to a transformer - PLEASE NOTE: do not exceed 6 Volts DC during operation: although not automatic, you can manually raise and lower the bridge using the direction lever
on the transformer, and you can stop and reverse direction of the bridge at any time. Carefully test the operation of the Cabin Micro Switch to stop the bridge in the “up” position.
31) Install the Lower Abutment Switch assembly on top of an abutment or pier (both sold separately), making sure it aligns with the “feet” at the end of the side girders when the bridge is in the down
position. Adjust the switch to turn off the motor just as the movable span touches down – be careful not to force the span too far and stall the motor. Test the operation; PLEASE NOTE: the motor must
shut off completely when the bridge reaches the up or down positions to prevent damage to the mechanism. Tighten the contact screws on both switches once you’re satisfied with the bridge operation.
The Cabin Sides (36, 37, 38) can be glued in place; the Shed Roof should be set in place so you can remove it to make adjustments or perform future maintenance.
Interlocking Tower Assembly
32) Glue Windows (79) and Doors (81) to Walls (74, 75, 76, 77). Using the raised ridge on the Base (73) to align parts, glue
Walls to Base and at inside corners where parts meet.
33) Glue Stairs (2x 83) to top of Large Platforms (2x 86). Glue Stairs (83, 84) to top of Small Platforms (2x 85) as shown.
Note the molded ledges on Left Tower Wall (75); glue the Large Platforms on top of the ledges and below the doors. To
prevent breakage, glue Long Handrail (90) to the inside of the Stairs on both Large Platforms at this time. Glue Small
Platforms to ledges on the right of the Wall; make sure Long Stairs touch Base.
34) PLEASE NOTE: Glue Outside Railings (2x 89) to the outside of the Platforms; Glue Railings 87 and
87A to the top of Platforms and to the Wall. Glue Inside Railing (88) to Wall and to Long Handrail (90).
35) Tower Roof (78) may be glued, or set in place if you wish to add lights or interior details (sold
separately).
2