The Crawler-Transporter thread

[JayP]

Great work By DaveS and JayP. I've started to model the Crawler-Transporter, MLP and the Space Shuttle Stack. Im not too sure how far to detail the models, as the platform it will be running on is limited. I'm started to hit dead ends when trying to get details shape and size of the hydraulics on each of the corners of the CT. I hoping L2 will have answers

I will save you some research. The publicly available information on the JEL cylinders gives us this;
Bore diameter: 20 in
Stroke Length 79 in
Normal operating pressure: 3000 psig
Emergency operating pressure: 4800 psig
Design Proof pressure: 6000 psig
Design burst pressure: 9000 psig

There aren’t any real drawings of the cylinders out there but there are a bunch of good photos on the KSC media pages. Most of the best ones are of the work done after the bearing failures found before the STS-112 roll out.

Looking at some typical cylinder design formulas, I came up with a wall thickness of the cylinder of around 3 to 3.5 inches depending on what factor of safety you want which gives a body diameter of 26 or 27 in. Assuming a hollow piston body with end caps (again, typical for a single acting cylinder like these) that gives us an empty cylinder weight of around 10,000 lbs. Looking at the geometry of the structure of the trucks the corner weldments, I get a center to center distance of the bearings at minimum stroke of 114 in and a max length 193 in.

If you’re interested in some math, the 20 in diameter and 3000 psig pressure gives a force per cylinder of 942,000 lbs. with a total thrust for all 16 cylinders of a bit over 15 million lbs. That’s 3 million lbs. for the suspended parts of the crawler (basically the center chassis and all the equipment contained within) and 12 million for the ML and vehicle, which is why CT-2 is being uprated with bigger, higher pressure cylinders for SLS.

The distance between the front most and rear most cylinders is 1194 inches. Some trigonometry tells us that the steepest angle the crawler could handle with the total 79 in stroke is 3.8 degrees. The slope of the hill leading up to the pad is 5% or 2.5 degrees which would only need a bit more than 52 in stroke so they have plenty of margins there.

I hope this helps you some and good luck on your project.

[desktopsimmer]

Thanks JayP most of information come from hours of wading through many documents on NTRS. I've also searched through images, both taken by members of the public and NASA.

The best two drawings of the complete assembly is on my blog. Tonight I planning on completing the surrounding walkway and safety rail. Hopefully I'll be able to post images.

[desktopsimmer]

Here's a puzzler for you all. I'm just modelling the walkway retractable step for getting on/off the CT and I've notice that there are two different version of retractable steps. My question is; it this a difference that been introduced over time to one or both CTs? Is it a difference Between CT-1 and CT-2?


[Edit]
The difference is one walk seen to be extended pass the retractable steps (walkway_01), the other is not (walkway_02)

[Edit2]
I'm modeling the CT that was used on STS-135

[JayP]

Here's a puzzler for you all. I'm just modelling the walkway retractable step for getting on/off the CT and I've notice that there are two different version of retractable steps. My question is; it this a difference that been introduced over time to one or both CTs? Is it a difference Between CT-1 and CT-2?

The platforms are the same on both crawlers. I've never found an explanation for the difference between the gangways on either side. The longer platform is on side 2 (the side with the control room) which is on the west side when the crawler is at the pad. I've always assumed that the extention was to mate up with some platform at either the pad or at one of the park sites so the opperators could walk from the crawler to the structure without having to go all the way down to the ground and back up, but that is just an assumption.

[desktopsimmer]

Thanks for the reply. I'm stumped as well. Thanks for the the reference drawing. This shows me difference and gives a rough scale to do the extension. I've noticed that the side view is reversed tot he top view, is this correct?

After looking at he picture, again, I've noticed that on the extended side (walkway_02.jpg), there appears to be a yellow section of the safety rail that is removable (towards the south side at the pad). However on the non extended side (walkway_01.jpg) it appears as a perfect mirror. I've added two yellow circles approximating the location. I cant figure way this is. Maybe ease of a maintenance task?

[JayP]

Thanks for the reply. I'm stumped as well. Thanks for the the reference drawing. This shows me difference and gives a rough scale to do the extension. I've noticed that the side view is reversed tot he top view, is this correct?

Yes. I found this image in a report somewhere. the drawing is correct but the side view should be reversed left to right.

After looking at he picture, again, I've noticed that on the extended side (walkway_02.jpg), there appears to be a yellow section of the safety rail that is removable (towards the south side at the pad). However on the non extended side (walkway_01.jpg) it appears as a perfect mirror. I've added two yellow circles approximating the location. I cant figure way this is. Maybe ease of a maintenance task?

Yes, those side rails are removable. They provide access to the alcoves behind them that lead to the interior spaces of the crawler. They are there to let them insert or remove equipment or supplies that are to big to bring up the gangways but are small enough that they don't need to remove the roof panels. there are removeable rails at the side 1 end of both the side 2 and 4 catwalks, not a perfect mirror. I have inluded 2 images that show both sides of CT-2 for comparison.

When you get to details like this there are a lot of little differences all around the crawlers. For instance, each corner has a different arangement of ladders and guard rails to access the top of the corner casting on accont of the different arangement of MPMs at each corner.

One difference between CT-1 and CT-2 is that CT-1 has narrowed catwalks alongside the gangways. You can see the jog in the railings in the first image in your original post above. CT-2's catwalks ar a constant width. CT-1 was eventually modified with the wider catwalks.

One problem with trying to research this stuff is that all the engineering data that NASA has is classified so we are limited to some concept drawings and photographs. Since things have changed over the years, it is hard to tell if some detail you see in a photograph is still there or was changed at some point. I've been trying to get them to let me crawl around one of them with a camera and a tape meassure, but they won't let me for some reason

[JayP]

I'm still working on my Solidworks model of the crawler on and off as work and life allows. Recently I have gone back to the gear trains. I think I have the final drive shaft resonably well done but I'm sort of stumped when it comes to the fourth intermediate shaft. Does anyone have any pictures or better drawing of those gearsets and how they are mounted in the gearcase? I have included the best drawing I can find below, but it is only one view and it doesn't help much. Does anyone know how it is mounted? The shaft and gears would have to come out upward thru the opening left by removing the dog house but the prominent holes thru the side frames have to have something to do with it.

Does anyone have any info on the gearcase itself and howq it was built? I know some parts of it are castings and some are welded plates like the rest of the side frames but I don't know the overall design.

Also, does anyone have data on the actual gerar ratios? I've included my spread sheet where I have attempted to work it out, but I would like to at least confirm if the numbers are correct or not.

Thanks for any help in advance.

[sprtnsky]

There aren’t any real drawings of the cylinders out there .

I thought there were some real good drawings of the Jel Cylinders out there, jus a matter of whom is not going to share.

[JayP]

Found an answer to one of my questions here;

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120003345_2012003532.pdf

now all I need is PDFs of the drawings listed... And all the rest of the drawings

[JayP]

A couple more detail questions, this time dealing with the stairs on the ends of the crawler that go up from the catwalks;

        A)   The stairway on side 3. (the one that was used to get to the ML in the Apollo days and was later shortened)
           a.      The platform that was added to the top for the shuttle. Is it a steel structure welded to the main frame of the crawler or is it an aluminum structure welded to the stairs and bolted to the main frame?
          b.      On that platform, there is a large disconnect box with a cable hanging off of it. I assume that is the AC power feed for the MLP but where does it connect to the MLP? The bottom of the MLP is just flat in the area where that platform would be.

        B)   The Stairway on side 1. (the one they added to access the MLP for the shuttle)
          a.   Is the structure of the staircase steel welded to the main structure below the catwalk with aluminum stair treads bolted on instead of a total aluminum construction? I know the beams on the top are bolted in.

        C)   Did they just repaint the support beams for the catwalk gangways the same blue as the shaw-box hoists on CT2?

[JayP]

Does anyone know the manufacturers (and model numbers if possible) of the purchased euipment for the operators cabs they built back in 2004? I'm talking about the things like the seats, windows, doors and interior lights. I know that they are standard marine equipment (the windhield wiper is a Wynn Type D Mk V unit) but I can't find them in any online catalogs. For instance, the drivers bolster seat has these distinctive grab rails, but I can't find a seat that has them. perhaps they have been discontinued since then.

[Hog]

A 3 minute blurb on the design, contract competition and subsequent building of the 2 Crawler Transporters. 

Starts at roughly 9:00 and ends at at approx. 13:00





Inside the NASA Crawler Transporter KSC Feb, 24, 2000 tour given by Craler Transporter Manager.

Part 1


Part 2
http://www.youtube.com/watch?feature=endscreen&NR=1&v=TvWz06BvO4A

Part 3
http://www.youtube.com/watch?NR=1&v=1uB5femx858&feature=endscreen



62 ft per gallon!!!

Enjoy!

[AndrewSTS]

62 ft per gallon!!!

Enjoy!

I'll be honest, I thought it was less!

[JayP]

I've been batting zero on information lately, but I'll give this a try. I've been working on the JEL / Steering / Corner bearings recently and I was wondering if anyone had a photos or information they could share on the arangement at the bottom of the pole at the center of the gimbal where it mounts to the truck body (see image attached)? It has to be some sort of joint that allows 3 degree of freedom movement, but I don't know if its a series of swivels or just a spherical bearing. Also, how are the steering and corner height sensors actually set up?

Thanks in advance.

[Longhorn John]

I've been batting zero on information lately, but I'll give this a try.

Your NTRS link is down too.

[JayP]

I've been batting zero on information lately, but I'll give this a try.

Your NTRS link is down too.

Yeah, I noticed. And I'm not expecting it to ever come back up reguardless of what the notice on the web page says. It's much easier for NASA to just cut off access than actually go thru every document in there and check for ITAR issues.

That's why I was hoping people here could help.

[civilguy]

Anyone know what material is used for the crawler pad connecting pins?

[sprtnsky]

can you post a picture of what your looking for.

[civilguy]

I don't have a picture. I'm curious what grade steel is used for the pins that connect the actual track pads together.

[sprtnsky]

is this what you are referring too ?