Author Topic: The Crawler-Transporter thread  (Read 254797 times)

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #300 on: 06/10/2011 09:20 pm »
The Discs attached to the shaft ends of the DC Propel motors are brake discs. Slighlty different from the type on cars, but close enough, just really bigger.

The Gear Cases house a gear reduction set of 4 intermediate reduction gears, the fifth is actually the sprocket, sprocket shaft and sprocket shaft drive gears.

The ratio is 168:1. 168 rotations of the drive motor produces 1 rotation of the sprocket.

Some documents call the propel motors "DC Traction Motors" but "Propel Motor" is usually the most accepted term.


The cab speed potentiometer reads in percent, from 0% to 100%. Each speed pot's output is just a little different and results in a different speed.
Other speed pot position factors are load, crawlerway gravel distribution, on or off a slope and of course how that particular crawler is feeling on any given day. Each CT has slightly different starting and stopping characteristics.

Online DaveS

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Re: The Crawler-Transporter thread
« Reply #301 on: 06/14/2011 06:13 pm »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg
« Last Edit: 06/14/2011 06:16 pm by DaveS »
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #302 on: 06/15/2011 03:19 am »
The Gear Cases house a gear reduction set of 4 intermediate reduction gears, the fifth is actually the sprocket, sprocket shaft and sprocket shaft drive gears.


The ratio is 168:1. 168 rotations of the drive motor produces 1 rotation of the sprocket.

My calculations must be off. Do you know the actual ratios of each reduction step and posibly the number of teeth on each gear? Like I said, I've never seen the actual numbers, but it would be helpful to know.

There are actually 5 reduction steps. The bevel gear set that conects the motor drive shaft to the gear box is the first one.
« Last Edit: 06/15/2011 04:22 pm by JayP »

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #303 on: 06/15/2011 03:22 am »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg
Judging by the angle of the stearing cylinders, its got to be pretty close to bottomed out.

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #304 on: 06/19/2011 09:21 pm »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg

No, th height does not equal 0.00 inches. The height of the CT in this photo is approx. 14 to 16 inches ave. height(travel height).

6 inches is the low end of the height as read on the ave. height meter.
It is possible to go a little lower, however the electrical and software stops would have to be overridden in order to reach the mechanical stop ring.

Online DaveS

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Re: The Crawler-Transporter thread
« Reply #305 on: 06/19/2011 09:23 pm »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg

No, th height does not equal 0.00 inches. The height of the CT in this photo is approx. 14 to 16 inches ave. height(travel height).

6 inches is the low end of the height as read on the ave. height meter.
It is possible to go a little lower, however the electrical and software stops would have to be overridden in order to reach the mechanical stop ring.

Thanks. What is the ave. height when jacked to docking and clearance heights?
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #306 on: 07/29/2011 01:31 am »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg

No, th height does not equal 0.00 inches. The height of the CT in this photo is approx. 14 to 16 inches ave. height(travel height).

6 inches is the low end of the height as read on the ave. height meter.
It is possible to go a little lower, however the electrical and software stops would have to be overridden in order to reach the mechanical stop ring.

Thanks. What is the ave. height when jacked to docking and clearance heights?

Sorry for taking so long to reply. Been very busy.

Ave. Height going under the MLP:  Approx.  9 inches. Sometimes a bit lower depending on the facility.

Ave. Height docking the MLP:  Approx.  36 to 38 inches. Depending on the facility. This gives approx. 18 inches between the bottom of the MLP guide pin base and the top of the mount mechanism.


Offline JayP

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Re: The Crawler-Transporter thread
« Reply #307 on: 09/18/2011 10:44 pm »
Can anyone tell me if these numbers are correct? I've put this together from all of the (admitedly scarce) information I can find plus some outright guesses from a few photos like the ones attached. Thanks in advance.

Edit; I updated the spreadsheet based on the realisation that they probably didn't stick to standard diametral pitches since these gears would not have to mesh with other standard gears and they could aford to make a special cutter for each different gear. I also added an image of a simplified solidworks model of the gear tran.
« Last Edit: 09/25/2011 06:17 am by JayP »

Offline Proponent

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Re: The Crawler-Transporter thread
« Reply #308 on: 09/19/2011 03:52 am »
What's the projected cost for upgrading the crawlers to handle the weight of SLS's 5-seg SRBs?

Online DaveS

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Re: The Crawler-Transporter thread
« Reply #309 on: 10/16/2011 10:22 am »
Thanks for the answers so far! Here's another. I have attached a photo of one of the CTs during a roadtest back in 2004 after the shoe replacements were done. Is this as low as the CT can go? I mean, does the height of the CT in the photo equal close to 0.00 on Average Height? Here's a link to the hi-res version: http://www-pao.ksc.nasa.gov/kscpao/images/large/04pd2681.jpg

No, th height does not equal 0.00 inches. The height of the CT in this photo is approx. 14 to 16 inches ave. height(travel height).

6 inches is the low end of the height as read on the ave. height meter.
It is possible to go a little lower, however the electrical and software stops would have to be overridden in order to reach the mechanical stop ring.

Thanks. What is the ave. height when jacked to docking and clearance heights?

Sorry for taking so long to reply. Been very busy.

Ave. Height going under the MLP:  Approx.  9 inches. Sometimes a bit lower depending on the facility.

Ave. Height docking the MLP:  Approx.  36 to 38 inches. Depending on the facility. This gives approx. 18 inches between the bottom of the MLP guide pin base and the top of the mount mechanism.


Sorry to bring this up again, but could you clear this up for me a bit? With docking height, I mean the ave. height when the CT is touching the interfaces on the bottom on the MLP.

And with clearance height I mean the ave. height when the MLP guide pins are clear of the mounts and ready to roll.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #310 on: 10/16/2011 03:57 pm »
Sorry to bring this up again, but could you clear this up for me a bit? With docking height, I mean the ave. height when the CT is touching the interfaces on the bottom on the MLP.

And with clearance height I mean the ave. height when the MLP guide pins are clear of the mounts and ready to roll.

Here is a drawing that may clear it up for you. It is the of the mount mechanisms that are on the underside of the MLP and form the interface with the top of the CT. The elevations refer to MSL which means Mean Sea Level and are measured at the original ML erection site (now the east and west referb sites along with the quonset hut between them) which is 8'-0" above MSL so you can take 8' off of those numbers

The drawing shows contact at 29'-4 1/2" (21'- 4 1/2"). Assuming that 20'-0" = 0 on the average height meter, that makes contact at 16.5. The drawing also shows that a height of 0 would give 10 3/4" clearance between the top of the positioning mechanisms and the bottom of the mount mechanism, but as GBCT says, they can't actually go that low. A height of 9 as he says will give a clearance of 1 3/4" when driving the crawler under the MLP.

As far as the height when lifted to clear the mounts, the pins in the center of the mounts are 13 1/2" long so an average height of at least 30 would be needed to clear them. That doesn't quite jibe with GBCT's numbers (an average height of 38 would mean an 8" clearance, not 18")

Not really an average height, but on the 5% slope up to the top of the pad, the difference between the heights at one end and the other would be 54". According to GBCT's post a page back, the allowable range is from 6" to 72". That gives a 12" wide band of available average height, from 27 to 39.
« Last Edit: 10/16/2011 04:50 pm by JayP »

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #311 on: 10/20/2011 02:38 am »
Average Height is: The Height of each corner summed and divded by 4. For Crawler purposes, each corner is measured from the stop ring up. This is "0".  6" is the lower stop point maintained by electrical, mechanical and software stops. You go much below 6" and equipment starts to get damaged.

When going under a MLP you must have 4" of clearance between the top of the Crawler interface mechanisms and the bottom of the MLP interface blocks. This equates to 9" on the cab and control room readouts. Depending on the Crawler, facility and individual MLP the reading can be slightly lower. When jacked to touch on the MLP interface block and the CT, the reading is about 18", again dependant on the Crawler, facility and individual MLP.

When raised off of the mounts, in a ready to propel(first motion) condition, the ave height reads 36-38", again dependant on the Crawler, facility and individual MLP. This will be approx 18" between the top of the mount and the bottom of the MLP Guide Pin attach base.(The actual guide pin is only 4" to 6" above the mount. never actually put a measure on that, just a SWAG).

Travel Height after leaving a facility is about 14" to 16". Travel height at the transition up and down the slope is 35-36" to allow for almost full extension and retraction. This gives the JEL system time to jack so it doesn't have to work so hard.

JayP's dwg appears to be an original MSFC or early KSC dwg. Those dwgs were masterpieces, blurry but accurate. The last time I measured a MLP interface block, can't remember if it was 1 or 3, the usable height of the block was about 4.5" to 5". again, accurate per the drawing.


The sprocket and gear photos appear to be from the 2004-2005 time frame when CT mods were in full swing. The gears looked almost like new. Very little damage or wear. A few sprockets were repaired, I think, overall things looked pretty good.


I don't have the SLS mod costs, don't know if they have been made public yet.

Hope this answers some questions.


Online DaveS

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Re: The Crawler-Transporter thread
« Reply #312 on: 10/21/2011 11:44 am »
GBCT#5: Thanks for the explanation! You don't happen to have any shots of the Engineer Control Room console displays do you? They seem to be Windows based if I'm not mistaken.
« Last Edit: 10/21/2011 11:45 am by DaveS »
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #313 on: 10/21/2011 04:42 pm »
GBCT, Thanks for the information. The drawing is a section of sheet 76 of drawing 75M-05120. It was drawn by Reynold Smith and Hills in 1964 for their bid package for the structural design of the MLs. It looks like some things may have changed a little between this drawing and what was finally built. From your dimensions, it looks like the heights of the ML pedestals are a 2 or 3 inches higher than was originally planed. The drawings are a bit hard to read after all this time, but they are good enough to recreate a CAD model of the components.

Speaking of questions, Can you give me any insight on the gear ratio question above? I have been looking everywhere, but I can't find anything definitive.

Speaking of the JEL system, How exactly does the system adjust for the angle of the trucks relative to the main chasis as the crawler moves up the hill? The memometer systems keep the main chassis level, but the trucks angle up to match the slope. I calculated that the JEL cylinders on the downhill side of any one truck are extended 5.69 inches more than the ones on the uphill side (see the section view below) I found this image showing a gimbal system in a report on the crawlers from the 70's but it doesn't explain how it works. Are the cylinders on each truck ported to gether so that they self adjust? (As the truck tilts, fluid flows from the uphill cylinders to the down hill ones and the average extension stays the same) Or is there some other system in play? The angular pot would only tell you what the angle is right now. If the cyinders were locked and the back end of the truck started lifting off the ground, it wouldn't tell you anything about that.

Thanks again
« Last Edit: 10/23/2011 03:22 pm by JayP »

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #314 on: 10/31/2011 12:15 am »
DaveS:
I'll have to dig out some Control Room Photos. There are 5 display terminals in the Control Room. They are windows based and very reliable.
Shortly there will be a few more display terminals added.

JayP:
Your dwgs show a side view of the Truck and Guide Tube with the JEL Cylinders. The Trucks turn about the Guide Tube, Jack up and down about the Guide Tube. Also, as your dwg depicts, the Trucks can adjust to a certain amount of unlevel ground, both side to side and end to end.
The gimble you read about is inside the Guide Tube on the top of the Cage. The Height Transducers and Steering Angle Transducers are located inside the Guide Tube. All are connected to a Square Tube that is inside the Cage thru the Gimble.  Your dwg is from the 60's or early 70's. The types of transducers depicted in that drawing are no longer used.

The Crawler levels and equalizes by two systems. Unloaded, the Manometer System pressure controls the level and equalization. Loaded, level and equalization is controlled by the pressure on the JEL Cylinders. Both Systems utilize the same algorithim for control.

Here's a photo of the Gimble attached to the Square Tube. Another of the Cage with nothing attached, ready for modification work to begin.

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #315 on: 10/31/2011 01:38 am »
GBCT,

 Thanks, that does explain things. I didn't know that the angle pot waas reading the STEARING angle, noty the tilt angles. I had assumed that they read the strearing angle from the linear pots on the stearing cylinders

Just checking that I have it right now, the system doesn't actually read or control the trucks pitch or roll angles. The 4 cylinders on each corner are plumbed together so that they will naturally adjust to an angle where the pressure on each cylinder is equal, right?

What kind of sensor are they using now instead of potentiometers? Hall effect sensors?

Offline JayP

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Re: The Crawler-Transporter thread
« Reply #316 on: 11/06/2011 06:20 pm »
I read somewhere that only one crawler is getting the gusset and JEL upgrades and the other is only getting life extensoion work. Is that trua and if so, which one is getting which?

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #317 on: 11/10/2011 12:58 am »
The Trucks are passive. No Pitch or roll control, only steering and height.
Correct on the plumbing.

Steering and Height sensors are hall effect.

Both Crawlers will get the shear web mod.

CT2 is undergoing life extension modifications.

If all goes well, CT1 should follow within the next year and a half.


Offline JayP

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Re: The Crawler-Transporter thread
« Reply #318 on: 11/12/2011 02:11 am »
Thanks again,

A couple of more questions,

 To increase the lifting capacity of the JEL system are they replacing them with bigger diameter cylinders or going with higher pressure or both?

 The shear webs that are getting modified, are they in the truck side frames?

 Looking at the photos of the new ML, the staircase on side 3 looks like it will be modified back to itís original design. Is that the case and are they doing that now or later?

 Speaking of the catwalks, I have scans of the latter sheets of the drawing but not the BOM. Are the catwalks and stairs aluminum weldments bolted to steel supports that are welded to the main structure? (I know that parts of the gangways are fiberglass pultrusions). Iím trying to get my SolidWorks model as accurate as possible.

Thanks,

Offline GBCT#5

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Re: The Crawler-Transporter thread
« Reply #319 on: 11/21/2011 01:48 am »
"To increase the lifting capacity of the JEL system are they replacing them with bigger diameter cylinders or going with higher pressure or both?"

Larger Diameter Cylinders. Depends on the booster we end up with for the pressures. I think the pressures will be greater, no matter what.


"The shear webs that are getting modified, are they in the truck side frames?"

Yes, shear webs are inside the trucks.


"Looking at the photos of the new ML, the staircase on side 3 looks like it will be modified back to itís original design. Is that the case and are they doing that now or later?"

Much later. My understanding is ML will undergo modifications first, then stairs. (Anything schedule-wise can change).


"Speaking of the catwalks, I have scans of the latter sheets of the drawing but not the BOM. Are the catwalks and stairs aluminum weldments bolted to steel supports that are welded to the main structure? (I know that parts of the gangways are fiberglass pultrusions). Iím trying to get my SolidWorks model as accurate as possible."

Steel supports are welded to the main structure. Correct, parts of the gang planks are fiberglass and aluminium.

If you and DaveS are building a Crawler somewhere, I want pictures when you are ready to roll! ;D



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