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[nsbob]

Mark:
Did you ever contact MTL directly and inquire about their 100 ton trucks?

Re: Microtrains 100 Ton Roller Bearing Truck

Reply #12 on: April 14, 2015, 06:29:33 PM »
Quote:
No soup for you.   

That truck would be the 1139 series.  We haven't gotten around to officially packaging that but if you contact the front office they can bundle them in quantities that match existing coupler-less trucks.  The rode on 36 in wheels.

Joe
MTL
[/b]

[Mark5]

Mark:
Did you ever contact MTL directly and inquire about their 100 ton trucks?

Yup, still trading emails.

[nkalanaga]

Part of the reason for the screw going in from the top is that the 36 inch wheels' axles are higher than the 33 inch, and there's less room for the screw.  I had several cars where a 1025 with the MT screws, or a 1015 with a flathead screw, rubbed the axles.  The solution to that was to use the 1925 and countersink the hole for a flathead screw.  A few finger twists with a 3/32 inch drill bit works fine.

That said, I don't like the idea of not being able to reach it either.

[wcfn100]

Pat said that for the cars with a die cast under frame, the flat and gon I assume, it's easier to thread into the plastic coupler box than the metal floor.  He also said he can make the bottom of the coupler box thinner if he doesn't have to have the thickness to counter sink the screw.  He didn't link this to using 36" wheels, but I can see where those would relate.


Jason

[cfritschle]

Part of the reason for the screw going in from the top is that the 36 inch wheels' axles are higher than the 33 inch, and there's less room for the screw.  I had several cars where a 1025 with the MT screws, or a 1015 with a flathead screw, rubbed the axles.  The solution to that was to use the 1925 and countersink the hole for a flathead screw.  A few finger twists with a 3/32 inch drill bit works fine.

That said, I don't like the idea of not being able to reach it either.

I am sorry, but I don't follow this reasoning.  The distance from the center of the axle and the wheel tread is greater for a 36 inch wheel than a 33 inch wheel.  Assuming the axles are the same diameter, so there should be an extra 1.5 scale inches of clearance with the 36 inch wheel.  (36 inch wheels have an 18 inch radius and 33 inch wheels have a 16.5 inch radius.)   

I can see where the 36 inch wheels would contact the side of the coupler box on sharp curves more readily than 33 inch wheels.

What am I missing?

Carter

[up1950s]

Who is going to make the flexi flats again ?

[wcfn100]

I am sorry, but I don't follow this reasoning.  The distance from the center of the axle and the wheel tread is greater for a 36 inch wheel than a 33 inch wheel.  Assuming the axles are the same diameter, so there should be an extra 1.5 scale inches of clearance with the 36 inch wheel.  (36 inch wheels have an 18 inch radius and 33 inch wheels have a 16.5 inch radius.)   

I can see where the 36 inch wheels would contact the side of the coupler box on sharp curves more readily than 33 inch wheels.

What am I missing?

Carter

What you're missing is that the coupler box has to stay at the same height off the top of the rails, so when you go from 33" wheels to 36" wheels, you raise the axle 1.5" closer to the bottom of the coupler pocket.  At some point they will interfere as the wheel gets larger.


Jason

[cfritschle]

What you're missing is that the coupler box has to stay at the same height off the top of the rails, so when you go from 33" wheels to 36" wheels, you raise the axle 1.5" closer to the bottom of the coupler pocket.  At some point they will interfere as the wheel gets larger.


Jason

Thanks Jason, after I posted I figured it must be something related to filing down the bolster or lowering the coupler box height since the distance from the axle to the coupler box would not be changing. 

However, 1.5 inches in N scale is 0.01 inches in the real world, so I am still uncertain as to why having the screw has to go in from the top is the best option.  Maybe using two screws (one on each side of the coupler box) to secure the coupler to the car would be a viable way the go.  I know that would mean more unsightly plastic showing as well as the cost of an extra screw, but I have had to replace too many broken couplers over the years to convert to a system that does not allow for maintenance.   

I know there is not much area to work with, and the photos of the converted hoppers look great, but I am going to have to pass on these for now.  Thanks Mark and others for posting the photos and info.

Carter

[wcfn100]

Thanks Jason, after I posted I figured it must be something related to filing down the bolster or lowering the coupler box height since the distance from the axle to the coupler box would not be changing. 

You still may not be getting it.  The distance from the axle to the coupler box does change.  As the wheel gets bigger, the axle moves higher, but the coupler box needs to stay in the same position relative to the rail to keep the coupler aligned.




Jason

[cfritschle]

You still may not be getting it.  The distance from the axle to the coupler box does change.  As the wheel gets bigger, the axle moves higher, but the coupler box needs to stay in the same position relative to the rail to keep the coupler aligned.




Jason

Jason,

I see the point you are trying to make, but that only happens if your are also modifying the trucks, the height of the coupler box and/or the bolster. 

The axle is always centered in the journal box, and so if you simply replace the 33 inch wheel sets with 36 inch wheel sets using the same truck without any other modifications, you raise the car and coupler by 0.01 inch.  The flanges on the 36 inch wheel may encounter clearance problems, but the distance from the axle to the coupler box remains unchanged unless the 36 wheels are mounted on larger diameter axles than the 33 inch wheels.

Carter

[wcfn100]

The axle is always centered in the journal box, and so if you simply replace the 33 inch wheel sets with 36 inch wheel sets using the same truck without any other modifications, you raise the car and coupler by 0.01 inch.  The flanges on the 36 inch wheel may encounter clearance problems, but the distance from the axle to the coupler box remains unchanged unless the 36 wheels are mounted on larger diameter axles than the 33 inch wheels.

Right, but now your coupler is no longer at the right height. For couplers to line up correctly, axles of 36" wheels are closer to the pocket than 33" wheels.  As I said in a previous post, Pat from Train-Worx said part of the reason to have the screw from the top was that the bottom of the box could be thinner.  I'm guessing this could be related.

Jason

[jagged ben]

I see the point you are trying to make, but that only happens if your are also modifying the trucks, the height of the coupler box and/or the bolster. 

We're talking about a manufacturer designing a car from scratch, so yeah he's going to be 'modifying' all those things.

[cfritschle]

We're talking about a manufacturer designing a car from scratch, so yeah he's going to be 'modifying' all those things.

I understand the need to get creative with the new tooling for new cars, but I was thinking about the about the Atlas 90 ton hopper shown in the photos that Mark5 posted.  Having the screw go in from the top is simply not very practical from a maintenance standpoint. 

I know how meticulous Pat is, so I am going to have to assume there was no other alternative, which is disappointing.   

Carter