Union Pacific Rotary Snow Plow 900081 – Part 4

To start this week I’d like to apologize for the lack of a post last week.  It had been a busy weekend at work and I simply ran out of time.

But the good news is I’ve made some, albeit small, progress on my UP Rotary Snow Plow project.  If you are new to this project you can start reading about it here.

Most of the body section is now drawn, although there is plenty of detail to add.  The one big space left to do was the rear of the unit.  And as most of the attention is drawn by the large fan at the front, the rear is often overlooked by photographers. This causes a problem for me to get information, and there’s a lot going on back there.  However thanks to Flickr and the photos of Dustin Holmes I have some great resource material to draw from, as you can see below.

Apart from the door, which is not centered on the body, and all of the grab irons and pipes, there are two lifting points which frame the door and the large fan at the top behind the grill.  This 48″ fan is a Dynavane blower, which delivers clean air to the motor, and traction motors which drive the cutting fan on the front.  This is necessary when the snow is falling hard and the air supply gets congested!

In order to model this and make sure the fan could be seen I’ve decided to make the mesh from etched brass. Below you can see the mesh closing off the rear of the body.

Behind the mesh will simply be the fan and a recessed area.  The sides of the body extend into the void as I need to alow space for the grab irons to run into and to give structural integrity to the body.

The actual fan will be printed as part of the body and therefore unable to rotate, but I don’t mind that, after all this is N Scale.

I will look at making the actual mesh as fine as possible so the light can get in and show the fan but from the render below you get the idea.

I’ve also added a coupling pocket for a Micro-Trains 1015 Body Mount coupler.  There will be a screw hole printed into the body to hold it in place.

I’ve also finished the directional cover which forces the snow either to the left or right.  This again will be made from etched brass as I want to be able to move it from side to side.  If I made this as a 3D printed part it would be too bulky and not look very realistic.  There will be a pair of holes on the cover which will clip over two pegs 3D printed onto the side of the exit chute.

Now I really need to get back to the chassis and finish working out how to modify it to fit in.  Once I have done that I’ll have another update for you.

Union Pacific Rotary Snow Plow 900081 – Part 3

In this week’s post, as promised last week, I’m going to share with you a bit more progress on with my UP 900081 Rotary Snow Plow kit.

A major part of a rotary snow plow is the fan at the front and for my kit not only do I want it to be functional but I also want it to look right.  And the UP 900081 has a very complex fan.

The red sections look smaller than the silver parts, however, they are the same.  Each blade has wings which fold out to alter the size of the blade.  All the red ones are folded in.  In the close up photograph below you can see the wings on blade number 6.  Blades 5 and 7 have had the wings removed.  You can also see the circular chute the snow is forced down behind the wings. The chute slopes away from the center of the fan towards the back of the fan chamber.  As the blades cut the snow it’s forced down these chutes and as each chute reaches the top of the rotation the snow is blasted out through the hole on the top of the fan chamber.

It would be very easy to simply make a flat disc and add details to the front but I wanted to replicate this detail as closely as I could, particularly the blades and the circular chutes.  3D printing gives me the ability to make this complex shape and maintain strength at a 1:160 scale.  In brass at this scale it would be a very difficult task.

The fan will be printed in one piece with a shaft at the back.  This will pass through the shell bulk head and be connected to a gear which will be driven by the motor.  The fan will also be a separate part from the main body to allow easy painting of both the fan and the fan chamber.  In the render below you can see the fan located in half of the body shell.

The exit chute is directly above the fan.  Above the exit chute will be the directional cover which will force the snow either to the left or right.  This cover will probably be made from etched brass as a 3D printed part will appear to be too thick. The actual wings on the fan haven’t been drawn yet either but I do intend to add this detail.

Because the fan is modeled fairly closely to the original you will be able to see the end of the circular chutes through the exit chute.  However in order to retain strength the circular chutes don’t go back as far as the original.  As a compromise I have added a cut out detail in the side of the fan which you will see as it rotates.

My next task, once the fan and exit chute is finished, will be to work out a reduction gear system so the motor speed is reduced in order to spin the fan at a slower speed.  And in order to do that I need to complete the power chassis and that’s something I’ll share with you in a later post.

New Axles for A Bachmann HO 4-8-4 Northern

I often get asked to have a look at damaged locomotives and see if there’s anything that can be done to repair them.  And I’m happy to say most of the time there is.  So this week I have another 3D printed part made specifically to repair a locomotive to share with you.

Bachmann make model locomotives in many scales and I normally work in N Scale but this time it’s HO and it’s a lot bigger than N!

This locomotive has a motor in the rear of the boiler which drives the rear axle.  The other wheels, just like the real thing, are driven by the connecting rods on the side.

However this particular model suffers from cracked axles causing an issue with the quartering. But what does that mean?

Well, as each driving wheel picks up power from the rails the axle needs to be electrically isolated to prevent it from shorting and this is done with a plastic axle.  Each metal wheel has a peg at the center which fixes into the plastic axle.  Below you can see the chassis upside-down with the base removed.  Between each driving wheel you can see the plastic axle and between the rear wheel set is an axle with a gear which is driven by the motor.

This all works well untill the plastic becomes weaker with age and the pressure of the wheels turning causes it to crack.  In the photo below you can see the crack line running through the original axle.

When it’s cracked like this the peg on the wheel will not be fixed tightly into the axle and the wheel can move differently to the wheel on the other side of the axle.  And it’s this which causes the quartering issue.  Quartering is a name given to the positioning of each wheel relative to the cylinder and piston.  In the image below you can see all the wheels are connected to the connecting rod at the same point.  Half way around the wheel on the left hand side, or at the 3rd quarter point.  And the piston will be all the way to the front of the cylinder.

At the same time on the other side of the locomotive the wheels are all connected at the top of the wheel or the 1st quarter point.  And the piston will be in the middle of the cylinder.

All steam engines are offset like this, although some are a bit different if they have more cylinders, but it’s this offset which ensures one cylinder can always push on the wheels no matter where the locomotive stops.  If both side rods were in the same position and the locomotive stopped with the cylinders in the middle of a stroke, it would be nearly impossible to get it going again.  So either side of an axle a driving wheel is positioned a quarter of a turn apart.   But if the axle doesn’t grip the wheels then they get out of sync, the side rods get jammed up and the locomotive stops moving.  And that is exactly what has happened to this locomotive.

However, there is a simple solution.  I have drawn a replacement set of axles and 3D printed them in Shapeways Frosted Ultra Detail material which is accurate and hard-wearing, so ideal for this replacement part.

Yes, I know the original had a square section in the middle but out of the three I’ve changed only one of them did and I don’t know why. The other two had round sections and as I could see no reason for it being square I made them all round. If anyone does know why, please get in touch.

And as you can see in the image of the chassis the axles fit well.  The wheels push in with a tight fit and stay at the correct quarter spacing.

I’ll be making these axles available soon in my Shapeways shop so if you also have a Bachmann HO 4-8-4 with spit axles you’ll be able to fix it and keep it running.

Union Pacific Rotary Snow Plow 900081 – Part 2

In this week’s post, as promised last week, I’m going to share with you which chassis I’m planning on using with my UP 900081 Rotary Snow Plow kit.

The reason why I plan on using a commercially available chassis is I want to make it easy to build and have reliable power pickup.  This will make powering the fan on the front much easier.  I can 3D print trucks, add contacts and fit metal wheels but when there’s something already available, which also has a motor and drive shafts, it seems the right way to go.  However the UP 900081, and UP 900082, have two different trucks front and back and the truck spacing doesn’t match anything else so it’s not going to be that easy.

The chassis I’ve chosen as a starting point is made by Kato and can be fitted in to all sorts of things but I think it was designed for Japanese street cars.  The 11-105 is the first of three including 11-106 and 11-107.  All three are the same just with different trucks.

The chassis are fairly cheap and available in lots of places online and in local hobby stores.  Plus they are great runners.

The plastic top is held on by four clips and simply pops off.  Underneath is a motor at one end and a worm gear and truck tower at the other.  There is a drive shaft connecting the two.

This means that only one truck in the chassis is powered by the motor, the other is free running but still picks up power, which is ideal for me.

With the top gear removed from the truck tower the chassis will become free rolling but maintain pickup from all the wheels.  This then allows the fan to be connected to the drive shaft.  This will also take a bit of figuring out as I want to incorporate a reduction gear box which will dramatically reduce the speed of the fan.  Although I intend to convert this to DCC, which will be very easy, simply telling the motor to run really slowly may cause it to stall or seem jerky. Having a gear box will allow the motor to run at a good speed whilst the fan slowly turns.

All that quality pickup will also make it easier to install sound as well, which is an interesting option.

As I said before, there are a few issues with the chassis. Firstly, the truck spacing.  This can be overcome by extending the chassis frame or simply 3D printing a longer one.

Secondly, the trucks themselves are the wrong type, and one doesn’t have enough wheels!  But this too can be overcome and again it will involve some 3D printed parts.  I haven’t decided yet whether to file down the existing side frame and stick on new ones or whether to 3D print a new truck outer section, but as the design develops that will become clear.  At this point you may be asking what is left of the original chassis?  Well, the motor and power pickup, which given the relative cheapness of the chassis is well worth it.

So I have a lot of design and drawing ahead of me on this project and next week hopefully I will have a bit more progress to share with you.

Union Pacific Rotary Snow Plow 900081 – Part 1

In last week’s post I told you about Rotary Snow Plows and my intention to make a model of UP 900081, the largest and most powerful rotary in the US.  You can find the post here.  In this week’s post I’ll go into a bit more detail about what I’m going to do.

UP 900081, as pictured below, is currently on display at the Museum of Transportation, St. Louis, Missouri, which is really useful as there are now lots of pictures available as reference material.

For my model the main body will be 3D printed in Shapeways FUD or FXD materials simply because to date this produces the best results.  And I’ll be setting the print orientation so the model is printed the right way up. (To see why this is important see my post about 3D print orientation here).

A lot of the surface area on the sides is flat so to help keep it smooth I’ll be making all the grab irons and ladders from etched brass. This has two advantages; firstly, anything sticking out of the side of the print needs support material underneath it in the print process and this can leave a shadow on the surface, and secondly, the etched parts look better. This has worked well on my other locomotives such as my Alco C855 as shown below.

This time I’m also going to include the mesh grills as an etched brass part.  The mesh frame will be 3D printed as part of the shell and a fine mesh will fit in behind.  This will allow you to see inside slightly as with the original.

Other details will also be made from etched brass such as the side window wipers and the unusual rotating windows on the front.  These special windows, shown in the photo below, rotated continuously preventing snow from settling and obstructing the windows.  (Photo of UP 900082 taken at Cheyenne 14th June 2000 by Don Strack),

In this close up on Don’s photo you can clearly see the rotating windows. My 3D printed shell will have a lip behind the window to receive a piece of clear plastic to form the glass and the etched rotating window will sit on top.

The big twelve-foot fan at the front will also be 3D printed but as a separate part as I want this to be able to rotate.  In fact in my model it will be powered. I will have more on how that will be done next week.

Above the fan is the directional chute which will also be a separate part so it can be flipped from left to right.

The trucks on the rotary are not standard either, well, the second one is as it’s recycled truck from a C&O steam tender, but I think the front truck was constructed from parts, making it unique to the rotary.

These will also be 3D printed but they will only be side frames as they will fit onto the chassis which will be a bought in.  Why not 3D print one?  Because I want good reliable power pickup and a motor to drive the fan.  The easiest way to do that is to use a powered chassis that works well.  I will also make a 3D printed chassis and trucks for anybody wants an unpowered version.

Behind the front truck is a snow plow which can be lowered to prevent snow building up under the fuel tank, but this is N Scale so that will be a 3D printed part of the shell.  It will also depend on how the new chassis fits in at that point.

In next week’s post I’ll share with you which chassis I’ll be using and how it will be connected up to the fan (if it arrives in the post in time).  For now I’ll leave you with a quick render of how my 3D model looks so far.

Union Pacific Rotary Snow Plows

Although I have may projects currently working through the system there is always room for one more and this week, given how cold it is and in some parts snowy, it seems the ideal time to start sharing with you my plans for an N Scale Union Pacific rotary snow plow.

This project is at the request of a fellow modeller but it’s one I have been thinking about for a while for myself, I think the rotarys are just fantastic!

So what are rotary snow plows?  In short they’re the last line of defense against heavy snow fall; when the snow’s falling and regular plows and shovels simply can’t do it the rotarys are called out to cut their way through. And they do literally cut their way through.  In the image below, taken by Steve Patterson and displayed on Railpictures you can see ex-DRGW steam rotary ‘OY’ being pushed by three steam locomotives.

The photo caption says: ‘In an attempt to open its line from winter snows, Cumbres & Toltec Scenic operated a triple-header rotary snow plow train on May 3, 1997. Three mikados are shoving Rotary OY as they near the deepest snow encountered on Windy Point, Colo., just short of the summit at Cumbres Pass which wouldn’t be achieved until the next day. The footprints in the snow ahead of the rotary are from pursuing photographers.’

Regular snow plows work by forcing the show aside and for the majority of areas this is just fine.  In winter months you can often see plows fitted to regular locomotives as with UP 9564 in the photo below. (Picture from Home Town by Handlebar).

But when it gets a bit deeper the plow has nowhere to push the snow so it needs to be lifted above.  This can be done with a larger dedicated plow which is pushed by locomotives as shown below. (Photo by Kevin Burkholder and displayed on Railpictures).

The large ‘scoop’ at the front pushes the snow up and out to the sides, the ‘wings’ (behind the plow with VB 103 marked on the side) can be adjusted to push the snow even further, and retracted to pass objects close to rails.  Plows like this come in all sorts of shapes and sizes as railroads tended to build their own out of freight cars, caboose and tenders.  The important thing is they needed to be heavy as hitting a snow bank at speed creates quite an impact as you can see in the video below. (courtesy of James Adeney from You Tube).

But when the snow gets really deep you simply can’t push through so out come the rotarys.  At the front, as shown below, is a large rotating cutting face or fan.  This breaks the snow down and forces it out a chute on the top.  The chute can be angled to the left or right and throws the snow far away from the railroad. (Photo by Alix Gillman and displayed on Railpictures).

The rotarys move much slower than the plows as they cut through but the only limitation is the amount of power to the fan and how much tractive effort is pushing it into the snow.  Typically rotarys are not self-propelled, all the power they generate is used to drive the fan, so they will often be seen with several power units pushing from behind.  The early rotarys were all steam-powered which gave the added advantage of heat.  Not only would the boiler provide steam to drive the fan but also to melt the ice which built up around the front.  The steam rotary below, pictured by Brian Snelson on Flicker, was built in 1898 and was used right up until 1968.  It’s typical of an early design with a  traditional steam engine tender behind for fuel and water.

As these machines were not in constant use, often only used every five to ten years, they were kept in running order but had little need for updating.  However as steam started to become obsolete on the class one railroads they started converting them to diesel and electric power.  A good example of this is the Southern Pacific with their route over Donner Pass.  They converted the actual rotary to electric power.  It was also coupled to a spare EMD F7 B unit which had its traction motors removed and all four installed into the rotary to power the fan.  The B unit produced the power for the fan motors.  A steam generator was also fitted to keep the front clear of ice and supply warmth to the crew.  Controls were added so the crew could control the pushing locomotives from up front.  In the image below you can see two rotarys and their F7B units, one at each end of some modern locomotives, as they wait for a passenger train to pass.  Up in the high mountains of Donner Pass they often worked like this so they could clear snow in both directions continuously. (Photo by Jake Miille Photography)

This photo is accompanied by a short video of the rotarys working on Donner Pass on February 25th, 2017.

Although the Union Pacific Railroad had many steam rotarys over the years purchased from specialist manufacturers, in the late 1950’s and 1960’s they also built some of their own and it’s one of these which I’m creating a model of.  As they started from scratch on their new rotarys it was easy to build them just how they wanted.

UP 900080 was constructed in 1958 at the UP Omaha shops.  It was built on the frame and rear truck from a retired ex C&O steam tender.  It has a 1750hp diesel engine to drive the 12′ rotary fan, weighs 347,240 pounds, is 50′-9″ long and 16′-8″ high. (Photo by Steve Patterson and displayed on Railpictures).

UP 900081 was constructed in 1966 at the UP Omaha shops again on the frame and rear truck from a retired ex C&O steam tender.  This time UP put in a 3000 hp diesel engine making this rotary the most powerful and weighing 367,400 pounds also the heaviest rotary in the United States.  It is 52′-2″ long, 17′ high and the rotary fan is 12′ in diameter.  (Photo by Joe Bracey and displayed on Railpictures).

UP 900082 was constructed in 1971 also at the UP Omaha shops. It has a 2500 hp diesel engine, weighs 284,500 pounds, is 55′-3″ length, 17′ high and has a rotary fan 12′ in diameter.  (Photo by Mike Danneman and displayed on Railpictures).

Out of the three 900080 and 900082 are still in service but sadly 900081 was damaged in 1994.  UP retired the rotary but donated it to the Museum of Transportation, St. Louis, Missouri later that year where it’s now on display.

As 900081 was the most powerful, 900082 currently holds that honor, it’s this one which I’m modeling, although it’s very similar to 900082 so it could be used for either.  The plan is to have a free rolling chassis but still have a motor inside to power the fan.  To do this I will most likely use a commercial chassis from a diesel locomotive and remove the drive gear from the truck towers.  Then I’ll connect the drive shaft to the fan.  Sounds very similar to what SP did with theirs!

Next week I’ll share with you some of the design drawings and go over some of the finer details I intend for the model.  To round-up this week’s post I’ll leave you with two videos of the White Pass & Yukon Railway’s steam rotary plow doing what it does best. (Both courtesy of Murray Lundberg from You Tube).