Chris's Marion 91 Steam Shovel

[gbritnell]

I would venture to guess that it's no different than the drive shaft in a car with two sets of universal joints.
It allows for initial angularity plus any lateral movement of the driveline.
gbritnell

[crueby]

The drive shafts go from the fixed position of the final gear axle end out to the end of the track drive sprocket axle, which can change position. The track assembly has a large center pivot at the end of the support arm from the frame, the one that has the Marion lettering carved in it. So, when going over uneven ground, the track assembly can pitch about that pivot. That changes both the angle and the distance that the drive shaft has to cover, so it has a universal joint at each end. The universal core X shaped piece is able to move in and out in a deep slot so it can adjust for length - you can see that piece at the end of the shaft in the rendering.


I'll go get a picture if how the track moves. Obviously there is a limit to how much angle it can handle, but this is a shovel not a Baja racer!

EDIT: added pictures

Okay, here is the track assembly as it goes over a 'rock'





As it pivots, the point where the drive shaft attaches, at the axle of the rear sprocket (left end in picture) will be moving in relation to the frame, so the drive shaft has to both pivot and change length.

I think the slight downward angle of the drive shaft at rest is due to the fact that the half of the drive gear is below the axle, and they needed to keep some ground clearance at the center of the frame, otherwise they could have lowered the final drive gear down to make the shaft level.
Hope that explains it?

[crueby]

This photo of the real machine gives a good view of how things angle down - the gears at the center had to be off the ground, and the shafts angle down slightly to the tracks.

Also, remember that the track system was a later retrofit 'kit' that Marion put out in 1923 to convert the shovels from railroad trucks to tracks - they reused the mount points for the side jackstands to attach the front tracks, and the rear tracks mounted to the same pivot that the original trucks used (the side bolsters are still there but now unused for the rear tracks) :

Originally, the rail trucks/wheels had a chain drive to their axles, that changed to this gear driven setup with a larger reduction in the gears since the tracks give a lot more rolling resistance than wheels on steel rails.

[crueby]

Catching up on the latest work - got the core of the travel gear chain dog clutch made. Started out by turning a length of bar down to diameter and drilling the axle hole. The end of the hole was expanded out slightly to leave room for the retaining ring that will keep the gear from sliding sideways on the shaft (the first half of the clutch is going to be attached to the side of the gear). Then put the chuck on the rotary table to mill the 3-fingered shape on the end. I centered the rotary table under the mill, and moved it back by half the diameter of the end mill bit plus another few thou to make the fit a loose one. Took a cut every 120 degrees to form one side of the gap.

Then moved the table back out to center and out another 1/2-diameter of the end mill, rotated the table to 60 degrees, and cut the other side of the gap, leaving a little waste section in the center of the gap.

Quick cleanup pass halfway back on the gap, and the shape is done for the first half of the clutch.

The first half was parted off, and the process repeated on the second half. On this half, the notch for the retaining ring was taken deeper, so the second half can slide past the ring and fully engage the first half. After the same shaping on the mill, a notch was cut in to take the sliding ring which connects to the handle lever, then it was also parted off.

Here are the two halves test fit against each other on the axle.

In order to mount the first half to the gear, the gear and clutch part were held on an arbor, one at a time, and drilled every 120 degrees on the rotary table for some alignment pins, and then loctited together.

Next step will be to cut the keyway in the second half and the side of the axle for the key that the part will slide on. The key is a loose fit into the clutch half, so that the part can slide side to side on the axle but not rotate. When the clutch halfs are engaged, that will transfer motion from the axle to the gear. I don't have a arbor press or broach, so will most likely cut the keyway into the clutch half with a jewelers saw and square file. The slot in the axle will be milled in.
Then I will start on the ring and handle that go to the control lever.

[Craig DeShong]

Still following along Chris, fantastic work!

[crueby]

Not much time in the metal shop today, but did manage to get the key for the dog clutch made and installed. The key itself was milled down from some 3/16" square bar I had, down to about .130, which was then inset into the side of the axle in (hopefully!) the proper place with a small end mill.



It was loctited in place, and then filed the slot into the moving portion of the dog clutch. Not having a arbor press and broaches, the slot was filed in with a small square needle file until it was a easy sliding fit.

With that part complete, I can start on the ring that goes in the slot in the clutch to connect to the control arm....

[crueby]

Somethine to look forward to (I am!) is some pictures to follow in a couple weeks of the real shovel. I got hold of the historical society with a proposal to supply a set of battery operated LED christmas lights to string around the perimeter of the shovel cab, boom, and tracks. They loved the idea, and I've got the supplies ordered (lights, batteries, clips to hold them on without holes/tape/etc). Should have things arranged for the install sometime in mid-November. Hopefully we get a decent weather day to put things up. The newer LED light strings will run for a couple months on a set of D-cells, they have timers to turn them on/off every day. Should make a nice attraction out of it for the holidays, maybe generate some more interest/funds for the restoration fund!

[ddmckee54]

Crueby:

The rendering in Reply #2306 has pins protruding from the "castings".  I assume those are there to show you that the bolt holes go where you think they go?  Or do you actually model the bolts too?

Don

[crueby]

Crueby:

The rendering in Reply #2306 has pins protruding from the "castings".  I assume those are there to show you that the bolt holes go where you think they go?  Or do you actually model the bolts too?

Don

Hi Don,


For parts bolted into place, I like to model in simple cylinder pins where the bolts will be. On larger bolts sometimes will add the nuts, but not always. It lets me see where the fasteners will be, and the pins let me do a cut combine operation to make the holes in both the main parts and what they attach to, so the hole locations will show on the blueprints. Also, they make it easier to see if there will be clearance at edges and inside corners for the heads and nuts.


Chris

[crueby]

For the control ring on the dog clutch, I bolted two short sections of steel bar together and drilled/bored out the center, so far looking a lot like a standard eccentric follower setup...

Mounted it on an arbor and used the rotary table on the mill to round the corners between the bolt flanges:

and test fit on the clutch, where it rides in the slot on one end:

Drilled for a couple short lengths of round bar for the pivots. These will be loctited in place, for now just slid into the holes till I can figure out how things will be assembled with the outer ring.

The outer control ring was bent out of some flat stock (took a couple tries to get it right shape), and the ends drilled for the pivots. The silver soldered it to a straight length, which will be used to attach it to the control lever already in place on the model.

After that cools and is cleaned up, I can see how the assembly will go together. There will be a hole drilled in the far end of the straight piece (and it will be trimmed to length) once it can be assembled onto the model and marked from the existing control lever end.

[crueby]

As hoped, after cleaning up the outer yoke from soldering and testing, the two halves of the control ring will spring into place around the clutch, so I went ahead and loctited the pins into the ring halves.

[crueby]

After some time to let the loctite set up, got the pieces of the clutch assembled. All is moving fine, so on to making the small retaining rings for the gear and axle...

[crueby]

The retaining rings are made and installed (2-56 grub screws), and the large gear is loctited in position. Once that cures, will give it a coat of paint (sorry Don) and then can spend an afternoon coaxing the bolts into position on the mounting blocks - going to be fussy getting all 8 of them inside the blocks and threaded down with an open end wrench. Then I can mark the handle on the control rod and get that cut/drilled to attach to the control linkage already in place on the model.

While waiting for loctite and paint to set up, will start laying out stock for the big 'casting' at the end of the travel gear train, at the lower center in this picture. That block holds the final two axles.

[Gas_mantle]

Looking great Chris 

[Ye-Ole Steam Dude]

Hello Chris,

That is another beautiful piece of work.

Have a great day,
Thomas