richhotrainRegarding the holes in the end braces for the cables, can you elaborate on that point a little more. I'm not sure that I understand your point. Rich
Rich,
Look at the top of the end of the bridge in the pic', there are three holes in the top end piece for the cables that lift the bridge. If You drilled them before gluing the end pieces on it will be easier to have both sides the same by using one as a template for the other side. Plus there will be less stress on them when pressing down on the bit to drill the holes. The holes in the CMR bridge were already in the end pieces:
Take Care!
Frank
zstripe Drill the holes in the end braces for the cables before attaching/gluing to ends......will make Your day so much easier. Also if You are going to run wires for power to a center shack, drill those holes now also, to accept a conduit for them, before adding any lattice bracing. I used 1/8'' brass tube.
Drill the holes in the end braces for the cables before attaching/gluing to ends......will make Your day so much easier. Also if You are going to run wires for power to a center shack, drill those holes now also, to accept a conduit for them, before adding any lattice bracing. I used 1/8'' brass tube.
Regarding the holes in the end braces for the cables, can you elaborate on that point a little more. I'm not sure that I understand your point.
Rich
Alton Junction
I'll answer Your other questions later.......But I want to point out.....Drill the holes in the end braces for the cables before attaching/gluing to ends......will make Your day so much easier. Also if You are going to run wires for power to a center shack, drill those holes now also, to accept a conduit for them, before adding any lattice bracing. I used 1/8'' brass tube.
Click on pic' for larger view and you can see the brass tube going through the deck girders.
Glued the truss sides to the girder assembly. Ready to attach the lacings and the top bracings.
zstripe PS: Finished one of the ship cranes yesterday.......what a challenge!
PS: Finished one of the ship cranes yesterday.......what a challenge!
zstripe Rich, Trust Me again.....1'' would be fine for 8. Remember, that there are 4 cables for each set of sheaves, which consist of four sheaves in each set of 8. One sheave holds one cable. The sheaves closest to the main span, are the motorized ones, the ones holding the counter-weight are idlers for a 8 pulley system. That's going to add up in cost....so be prepared. The CMR bridge uses 3 cable sheaves and only 4 sets, no idler sets. The CMR used 0.032'' Teflon coated music wire for the cables. The teflon coating made it easier to glue to the sheaves,bridge,counter-weght. Frank
Trust Me again.....1'' would be fine for 8. Remember, that there are 4 cables for each set of sheaves, which consist of four sheaves in each set of 8. One sheave holds one cable. The sheaves closest to the main span, are the motorized ones, the ones holding the counter-weight are idlers for a 8 pulley system. That's going to add up in cost....so be prepared. The CMR bridge uses 3 cable sheaves and only 4 sets, no idler sets. The CMR used 0.032'' Teflon coated music wire for the cables. The teflon coating made it easier to glue to the sheaves,bridge,counter-weght.
Although I am working in HO scale, I have to take into account that my entire vertical lift bridge project will be scaled smaller than the prototype equivalent.
For example, the prototype truss span would be 37.6245" in HO scale, but the bridge as I am kitbashing it will be 29.50". That translates to 78.4% of the prototype. So, a 2" sheave would scale down to a little more than a 1.5" diameter sheave. I will settle for 1" and purchase the Tichy sheaves.
mbinsewi I know Wayne asked this once, but are you going to build the towers at the 47 degree angle, to the river?
I know Wayne asked this once, but are you going to build the towers at the 47 degree angle, to the river?
On the prototype, the South Branch of the Chicago River runs on a soutwest-northeast angle, whereas the Pennsylvania Railroad tracks (double mainline) cross the river on a due north-south line. Not being an engineer, I am not sure why the bridge and towers were skewed, but they were in order to follow the banks of the river.
On my layout, I am designing the river and the bridge to run exactly perpendicular to each other. This does not trouble me because my layout does not exactly replicate the prototype. The layout closely simulates the prototype, but it is not an exact replica.
I love old construction pictures. I don't see any copyright problems with this one.
Those are some huge sheaves.
Mike.
My You Tube
zstripe When You are ready to do the hoist platforms and are looking for pulley's (sheaves) Tichy just came out with some interesting ones that should work. The CMR bridge has 7/8'' size for referance
When You are ready to do the hoist platforms and are looking for pulley's (sheaves) Tichy just came out with some interesting ones that should work. The CMR bridge has 7/8'' size for referance
zstripe When You are ready to do the hoist platforms and are looking for pulley's (sheaves) Tichy just came out with some interesting ones that should work. Look for them in this link I'll post. Keep link for future use. The CMR bridge has 7/8'' size for referance: https://www.tichytraingroup.com/WhatsNew.aspx
When You are ready to do the hoist platforms and are looking for pulley's (sheaves) Tichy just came out with some interesting ones that should work. Look for them in this link I'll post. Keep link for future use. The CMR bridge has 7/8'' size for referance:
https://www.tichytraingroup.com/WhatsNew.aspx
I have been collecting parts in anticipation of building the towers. Finding sheaves has been a problem. I have discovered Crow River Products which manufactures sheaves, so that is an alternative, but I really like the Tichy offerings.
Thanks again for the link.
Looks good.....now You are doing some constructive thinking!
BTW: When You are ready to do the hoist platforms and are looking for pulley's (sheaves) Tichy just came out with some interesting ones that should work. Look for them in this link I'll post. Keep link for future use. The CMR bridge has 7/8'' size for referance:
richhotrain zstripe richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard. Rich, Like I said in My PM.......The X sections are the main vertical stress part of the bridge. The 60/40 arrangement was to offset the stress on the X sections where the girders would meet, instead of having them directly over a joint, like in a hinge. Sort of like a reversing section on track where they tell you to stagger the joints......not directly across from one another. What You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck as I also suggested in My PM. Don't over think this.....It's not that hard. Take Care! Frank Frank, thanks for that reply. As you know, I overthink everything. I had considered what you pointed out about stress on the x-sections. That would certainly be true on a real bridge, but stress on an HO scale model??? Rich
zstripe richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard. Rich, Like I said in My PM.......The X sections are the main vertical stress part of the bridge. The 60/40 arrangement was to offset the stress on the X sections where the girders would meet, instead of having them directly over a joint, like in a hinge. Sort of like a reversing section on track where they tell you to stagger the joints......not directly across from one another. What You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck as I also suggested in My PM. Don't over think this.....It's not that hard. Take Care! Frank
richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard.
Like I said in My PM.......The X sections are the main vertical stress part of the bridge. The 60/40 arrangement was to offset the stress on the X sections where the girders would meet, instead of having them directly over a joint, like in a hinge. Sort of like a reversing section on track where they tell you to stagger the joints......not directly across from one another.
What You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck as I also suggested in My PM. Don't over think this.....It's not that hard.
Frank, thanks for that reply. As you know, I overthink everything.
I had considered what you pointed out about stress on the x-sections. That would certainly be true on a real bridge, but stress on an HO scale model???
richhotrain zstripe You are doing a fine job, Rich...... Take Your time...... Frank Thanks, Frank. Your CMR vertical lift bridge is my inspiration for this project. Rich
zstripe You are doing a fine job, Rich...... Take Your time...... Frank
You are doing a fine job, Rich......
Take Your time......
Thanks, Frank. Your CMR vertical lift bridge is my inspiration for this project.
Trust Me! Building that vertical lift bridge, was a cake walk, compared to building the fine detail on My ship....especially in the size of the parts in the etched brass detail:
Track fiddler Again.... Factory. That Pratt Bridge has your signature written all over it Rich. I like it TF
Again.... Factory.
That Pratt Bridge has your signature written all over it Rich. I like it
TF
I completed the modification of the four box ends to the bridge. Here is a photo of the completed truss side.
Here is a close up view of the boxed end.
I am pretty pleased with the result. Now, i need to move on and complete the installation of the top and bottom chords, the vertical and diagonal lacings, and then start construction of the expanded girders that support the truss sides and tracks.
mbinsewi richhotrain I had actually considered naming my variation as the Arched Rich Pratt Truss bridge Nice work Rich. I can see it now........... " Ladies and gentleman, before you stands a brilliant example of bridge design from the famous engineering father-son team of Caleb Pratt, and his son, Thomas Willis Pratt. I might point out, that a footnote in history gives Thomas Pratt's often rebellious and unrully step child, Rich, credit for the "squared off" end design, allowing for the main span to be incorporated into the vertical lift bridge that stands before you." Mike.
richhotrain I had actually considered naming my variation as the Arched Rich Pratt Truss bridge
Nice work Rich. I can see it now...........
" Ladies and gentleman, before you stands a brilliant example of bridge design from the famous engineering father-son team of Caleb Pratt, and his son, Thomas Willis Pratt. I might point out, that a footnote in history gives Thomas Pratt's often rebellious and unrully step child, Rich, credit for the "squared off" end design, allowing for the main span to be incorporated into the vertical lift bridge that stands before you."
Rich Pratt
Track fiddler What an accomplishment! Your bridge section looks Factory. You should be proud. You have succeeded in an area where I threw in the towel. The Webster dictionary should be changed. When one looks up the definition of perseverance, It should read: Rich's Pratt Truss Bridge modification TF
What an accomplishment! Your bridge section looks Factory. You should be proud. You have succeeded in an area where I threw in the towel.
The Webster dictionary should be changed. When one looks up the definition of perseverance, It should read: Rich's Pratt Truss Bridge modification
Speaking of Webster's Dictionary, I was looking at the various types of Pratt bridges on line, and I was surprised at the number of variations and the names assigned to them. I had actually considered naming my variation as the Arched Rich Pratt Truss bridge once I box the end sections.
Here is the end section of the Arched Pratt Truss bridge, as Walthers designed it.
I need to form a box on the end sections in order to provide a top horizontal surface to connect the tower cables. Here is what I am going for.
This is going to require some cutting and sawing and fitting to pull this off.
zstripe Looks good so far Richie........ Back to My ship...... Take Care! Frank
Looks good so far Richie........
Back to My ship......
richhotrain I successfully completed the addition of the third center x-braced section on both sides of the truss bridge, as seen in the following photos.
I successfully completed the addition of the third center x-braced section on both sides of the truss bridge, as seen in the following photos.
Now, I need to tackle one more aspect of the bridge to conform it to the shape of a vertical lift bridge. That will require modifying the angled ends of the sides to box shapes to accommodate the tower cables that lift the bridge.
BigDaddy I was going to suggest modifying it to a Baltimore Truss. I could find a really good picture on bridgehunter.com. There is so much iron work here, I don't know what I'm looking at
I was going to suggest modifying it to a Baltimore Truss. I could find a really good picture on bridgehunter.com.
There is so much iron work here, I don't know what I'm looking at
BigDaddyThere is so much iron work here, I don't know what I'm looking at
THIS was always one of the bridges I found to be fascinating. A bridge within a bridge:
http://www.trainmaster.ch/Z-425.htm
https://www.brasstrains.com/classic/Product/Detail/033937/HO-OMI-GN-BN-BNSF-416-foot-Bridge-in-a-Bridge-WOW
Cheers, Ed
Henry
COB Potomac & Northern
Shenandoah Valley
Cut the x-braced sections from the 2nd kit. Now. to glue them in place.