kelvin james said...
I still think your best bet is the centrifugal clutch brake. You can use a speed increase gear head to bring the rpm activation down to a slow speed, approx. 50 to 60 rpm.
Kelvin, that was my first choice, but I couldn't find a clutch brake with a low enough RPM, even with gearing.· 1200 rpm was the smallest I found, which would require a 20:1 gear ratio.
One guy here at the office suggested a gear 3:1 that drove a big fan.· The faster it went the more aire resistance there would be.
Please, no matter what you do...
Post a sign that clearly indicated the maximum number of passengers at any one time. At the top landing and at the bottom. My guess is that one or two adults until you have things really sorted out. If you are moving heavy stuff, do so without people on board.
It is all too easy after a party to have six people crowd into what you have for a quick ride down. I have doubts that the gear boxes and braking have that all worked out. Cables are quite strong and most likely the least of your worries.
Again, counter weight tremendously improves your safety and control. Steel/cast iron is double the mass of concrete; so it is the most compact cheap counter weight. Concrete and aluminum are nearly the same mass. Ideally, you may be able to have an emergency brake that grabs the counter weight's cable.
Having the twin cables is fairly good. But if the winches are not rated to pull the whole load individually; a failure of one may cascade into a failure of the second. Significant redundancy is the usually primary path to safety. I do realize it is costly, but go the extra distance and have a system that you can fully trust; even when you are not there.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
After looking at your videos I would be concerned about the possiblity of the cart tipping or derailing. Do you have a way to keep the wheels from coming off the track? You would need something that cups the bottom of the track. I assume the supports for the tracks are directly below the center, so your anti-derailment device would have to hang below either side of track with a gap in the middle. This could be part of the braking system as well -- sort of like caliper brakes on a bicyicle.
In the case of both cables failing, the braking action will tend to cause the cart to tip over on the downhill side. It is important that the anti-derailing device prevents this from happening. You could sense the tension of the cables by how much they can be deflected, similar to the way someone tests the tension on a fanbelt by pushing on it. You could build a tension detector that pushes on a normally-open switch. As long as the switch is closed it will energize a solenoid that keeps the brakes open. The brakes will engage if one of the two switches opens, or the circuit loses power, or a wire breaks. I would hang the tension sensors on the cables near the attachment point to the cart. I wouldn't put tension sensors inline with the cable. This would just introduce another possible failure mode.
To me, the possbility of tipping is a bigger issue. If there are four adults on the cart, and everyone leans over the railing at the same time this could produce enough leverage to tip the cart sideways. If everyone leans over the downhill railing the uphill wheels could raise up from the track. The tension on the cables should keep the cart from tipping backwards, but the uphill wheels could derail. You could reduce this possbility by raising the height of your safety rail, but I still think there should be a device to keep the wheels on the track.
Dave, its actually pretty stable, and the cables run through the top part of the cart down to the lower side. Also, I have replaced the wheels from the video with wheels that I posted on one of the earlier replies. This lowered the cart about 6 inches, which increased the stability even more.
Is it possible to turn it over? Yes, but they would really need to try to do so. It weighs about 200-300 lbs without anyone in it. It is 32 inches wide, and the rails are 30 inches apart on center. When I work on it and try to lift one side to get access to work on a wheel or whatever, I nearly strain my back to lift it. Plus, the uphill portion is angled, to get closer to the cart.
if it does tip over, it would be a somewhat soft landing. Its a forest floor and 2/3 of the way the cart is only 6 inches to 2 feet above the ground.
I can see your point of view tho. The videos look worse then it actually is. Plus, we now have benches on the thing, so stting increases the lower center of gravity.
I'm just thinking of some worse case scenarios. I agree, the cart "probably" won't derail. However, if someone wanted to try to tip the cart for fun they could stand outside the railing and lean out. The moment arm of the cart is only 15 inches. Two 175-pound guys could tip the cart if their center of mass was about 13 inches outside of the cart. Of course, a 4-foot fall to soft ground probably won't hurt them, but a 300 pound cart falling on them might sting a bit.
Also, attaching the cable to the back of the cart actually makes it more likely that it will tip backwards when the cart first starts moving. If four 175-pound guys were at the back of the cart its center of mass would be a foot or so in front of the back wheels, and about 5 or 6 feet above the wheels. A quick tug would send it tumbling backwards. The only thing keeping it from tumbling would be the cable pushing against the front of the cart. It would be like pulling the rug out from under someone. If you pull slowly they won't fall, but a quick tug will send them tumbling.
If it were me I would put some sort of postive retention on the wheels to ensure that the cart could never tip or derail.
Dave, the cables go through the topside of the cart (just below the floor) , and then back to the lower side wheels, bolted to steel. So the front is actuall held down by the tension of the cable. So, in a sense, it is doing what you mentioned. Its impossible to tip the cart back without breaking the front of the cart from the cables.
Also, I know this will stir debate, but to keep the cables equallay taut, each cable is attached to its side of the cart, and another segment of cable about 6 feet long is attached to each of these cables, and then through two pulleys near the back of the cart. Therefore, the tension is maintained, so if one spool wraps over but the other one doesnt, the 6 foot cable distributes the tension evenly. Some people look at the pulleys and say "ah, if one cable breaks, it will roll through the pulleys and let loose" but thats not the case because each spool dead ends onto the cart, and its only the segment that is on pulleys. I hope I didn't confuse.
I realize this is a little off topic so I'll try to add something worthwhile at the bottom of my post:
Where did you get those buttons? I want some! By "Those Buttons" I mean the buttons on your control box, very professional looking!
worthwhile Part:
Thinking... Thinking... Ok, Here's a plan, Let's assume your place a new rail on the elevator, I'm sure you could rig a device that when the towing lines went lax(Ie, use some type of counter springs to rule our just general taughtness by the shear weight of the lines) a spring loaded brake engaged, but would not engage at the top or bottom because some type of physical barrier would stop that process. I think that might work.
DiablodeMorte said...
I realize this is a little off topic so I'll try to add something worthwhile at the bottom of my post:
Where did you get those buttons? I want some! By "Those Buttons" I mean the buttons on your control box, very professional looking!
worthwhile Part:
Thinking... Thinking... Ok, Here's a plan, Let's assume your place a new rail on the elevator, I'm sure you could rig a device that when the towing lines went lax(Ie, use some type of counter springs to rule our just general taughtness by the shear weight of the lines) a spring loaded brake engaged, but would not engage at the top or bottom because some type of physical barrier would stop that process. I think that might work.
My dad runs a panel shop in Chattanooga.· They use those buttons all the time in all of their work.· I'll try to find out the name of the supplier and will let you know.· I think it could be from Grainger.
The remote control is actually a small panel that has those buttons wired into a linearcorp remote, which has 4 buttons.· We currently only use 3, but I hope to put a center stopping point, so we may need to add a button to it.
We are adding a lower deck area for the cart to stop at (near bottom of the house for firewood etc).· The cart now either goes all up, or all down.· At the bottom of the lift, there's a button to bring the empty cart down, and vise versa at the top.· We do all of this with the motor controller which although it is very powerful, is somewhat limited in conditional processing.
If we have a midpoint stop, I need a way to "call" the cart to the new landing.· I don't want my kids to go through the decision process of "Up" or "Down".· I need one button to bring it, so somehow I need some logical process to decide, to send up, or send down.
Therefore, using a stamp with a Hall Sensor I can determine the RPM for the original problem proposed, as well as determining the location of the cart (there are 42 spool rotations from top to bottom).· If I know the location, via relays I can:
inactivate the UP button if it is near the top (we have some safety here already, but I'd love to have the added safety feature).
inactivate the DOWN button if it is near the bottom.
control whether to activate the stop switches at a new mid point.
track the last 10 positions when the the upper or lower RTS switches are hit (these tell the cart to slow down and come to a stop) so that if the value is passed by with no RTS, it can assume there is a fault and execute a shutdown.
I have 4x20 LCD display.· We can display current RPM and location of the cart, and perhaps fault conditions that we detect.
Dad and I have discussed it, and we are going to have a series of relays that will allow us to "switch over" to a stamp solution.· In otherwords, if our stamp fails, we can turn off a switch and it will go back to the current operation which seems to work fairly reliably.
My research has shown that the PLC BS2 panel is the one for me.· The control box already has a 24volt bus.· Now I need to figure out which of the stamps to get, the BS2 at a minimum.
I hope that now I've decided to go with a stamp, I can get as much good help·on my stamp development as I have on other potential solutions!
Looking around the net for manufactures of hoist trams, i found some interesting things. Looks like there is a safety code for these devices, but i guess as long as an inspector doesn't come around where you are, or you are not worried about insurance issues, you are okay. Take a look at the safety features on the link provided, they do have the clutch brake, and a lot more than that. Don't take for granted that your cables and motor drive are accident proof.
kelvin james said...
Looking around the net for manufactures of hoist trams, i found some interesting things. Looks like there is a safety code for these devices, but i guess as long as an inspector doesn't come around where you are, or you are not worried about insurance issues, you are okay. Take a look at the safety features on the link provided, they do have the clutch brake, and a lot more than that. Don't take for granted that your cables and motor drive are accident proof.
Yes, you are referring to ASME code A17.1, section 513.·
I have seen many of those sites, but hadn't seen that one before.· I liked that cable track design where the cart sits in between.· I can only imagine how much concrete they would need to keep those cables tight.
We initially priced some of those systems, but they wanted close to 30 grand for a complete system (installation not included).· We built ours for under 7k.
I find the Munsonworks system interesting in what it is lacking.
It doesn't have a second cable. And it doesn't have a counterweight system.
I still prefer having the counterweight as it really will conserve on your power bill as well as reducing stresses on the primary drive systems to a minimum. In the long run it might actually recover its own costs.
I live in Taiwan and we have many [noparse][[/noparse]likely thousands] of small low tech elevators that rely on a single winch system. The tracks actually lift away from the ground floor to allow auto parking. Many building owners use these as freight elevators to store goods up to 5 floors about a ground store outlet. It seems to work fine as long as the traffic is not intense and the users are aware of the limitations.
Forgive me, but I assumed that this was an main entry point into the home, rather than backyard access. I happened to have a cousin that had a home on a sea cliff which did have such a main entry lift that delightfully ran above a rhodedenron garden as it decended from parking to the main entry.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Forgive me, but I assumed that this was an main entry point into the home, rather than backyard access. I happened to have a cousin that had a home on a sea cliff which did have such a main entry lift that delightfully ran above a rhodedenron garden as it decended from parking to the main entry.
No, its access to my boat dock, and hopefully access to my subbasement if I can add another landing platform.· We have the first floor (and a 2nd) where the tram starts, a basement level, and a subbasement level which is like 2 floors high.· From the base of the house, you climb 3 flights of stairs to get to the first floor.· And thats once you are at the base of the house.· Its quite a climb up the hill just to get to that point.· The tram gets us up 90 feet in the vertical plane.· I might add a counterweight later on, but currently (no pun intended) the electric bills aren't that high.· By using 220 volts 3 phase with PWM, its pretty efficient.
jeffjohnvol,
What you need to do is have a mechanical brake setup on the cart itself and you can use a braking system like on a old elevator its the same principle as a steam engine govenor. The balls on the end of the vertical rod spin because its linked to the shaft that has the wheels on it if it spins to fast the balls will pull outward and push down on the rod inside of the shaft and apply the brakes. I hope you can understand how it works with such a plain drawing.
bennettdan, yes, I have seen one of these work before and I understand the drawing. Part of the problem though is the rail is 2.5" schedule 40 pipe. Getting traction to spin the wheel on that pipe for a regulator like that may be difficult to manage. The current wheels are just casters, so there is no drive shaft to attach to. The attachment is a picture of the wheels I put on this weekend, and got rid of those other single wheels.
Given the fact that the pipe could be wet, rusty, dusty or some other situation that could prevent traction in an outdoor environment, I would be worried about tuning such a mechanical control system. Plus, given the fact that I can adjust the speed through the controller, I might have to fine tune when changing speeds. In theory that regulator would work, as an incremental brake or pulling a pin, but I would prefer a more exact solution, hence RPM measurement at the top.
Thanks!
Looking at the pics, you could add 4 more wheels to keep the cart from "bouncing" off of the rails;
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Leaving just the bottom center wheels off for rail support, the two bottom sets would not have to be as tight to rail as well..
Some one liked the switches you used, here is a source for totally waterproof digital ready switches for industrial use.
Looking at the pics, you could add 4 more wheels to keep the cart from "bouncing" off of the rails;
...T.T.T
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S--.O.--S ...."periods are for screen formatting"
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...B...B
Leaving just the bottom center wheels off for rail support, the two bottom sets would not have to be as tight to rail as well..
Some one liked the switches you used, here is a source for totally waterproof digital ready switches for industrial use.
Thanks Bob.· Actually, the angle iron that the pipes are welded to prevent us from putting wheels underneath the pipe.· If you look at the picture that I attached on an earlier post, you can see that I've increased the wheels from 4 total to 40.· They are very stable and don't bounce at all.
I'll save that link for other switches should I need them.· The ones I am using are industrial grade and rainproof.·
Actually, when I got my permit for the dock, I forgot to put in the request for the concrete pad that the rails are on. So, I told TVA (local lake authority) that the pipes were electrical conduit for my power. And it doubles as a road for my cart, lol. They were okay with it. I would never be able to sell these of course, and they don't have building inspectors where I'm at.
DiablodeMorte said...
I realize this is a little off topic so I'll try to add something worthwhile at the bottom of my post:
Where did you get those buttons? I want some! By "Those Buttons" I mean the buttons on your control box, very professional looking!
From my dad:
Jeff,
The switches are made by C3 Controls in Beaver, PA.
Phone 724-775-7926, fax 724-775-5283.
They are NEMA 4 rated and can be provided with Class 1 Div. 2 explosion proof contacts.
Here is an "idea" that no one has probably considered yet. This would be for a self contained safety brake system on the tram itself, independant of the drive system. Since it is outside, a gps could monitor the rate of acceleration and decent of elevation. The gps data would be watched by a stamp, and depending if the maximum values are exceeded, the stamp would activate an electric brake on the tram itself. You could have the tram stop if the gps lost the signal also, as an extra precaution. If you have a portable gps, or can borrow one, take it on the tram with you and check the location and elevation resolution, as the tram is moving down the track ( like how fast the info is being updated ) WAAS should be around 10 ft with a good signal fix. A 12 volt car battery has plenty of amps to hold a brake ( solenoid ), and holds the charge for a good time if not being used, other than powering the electronics if required. There are variables like the elements and mechanics to be considered, but it may be an idea to keep in mind. Lots of gps info on the forum here.
Thanks Kelvin. That could work, but it would defeat my goal not to have any battery or something I have to charge on the cart. Solar charging isn't much of an option either, because we are behind a mountain and under a lot of trees.
I also have additional reasons now to use a stamp other than the safety issue as discussed above.
Some other thoughts, ---- Instead of the hall effect sensor, consider an industrial type optical quadrature encoder, such as sealed Grayhill to monitor the drum shaft. You don't need a high count per revolution one, possibly a 64 or less will do. This will give the option of detecting which way the drum is turning, which will come in useful, and give a faster response time. Also, the mobo stamp may be worth a look, it has coprocessors to read an encoder ( Parallax can correct me if i am wrong ) or other sensors, freeing up the stamp to do other things.
kelvin james said...
Some other thoughts, ---- Instead of the hall effect sensor, consider an industrial type optical quadrature encoder, such as sealed Grayhill to monitor the drum shaft. You don't need a high count per revolution one, possibly a 64 or less will do. This will give the option of detecting which way the drum is turning, which will come in useful, and give a faster response time. Also, the mobo stamp may be worth a look, it has coprocessors to read an encoder ( Parallax can correct me if i am wrong ) or other sensors, freeing up the stamp to do other things.
Kelvin, I've been googling quadrature encoders and am very interested in this.· I hadn't considered determining direction.· I'll keep looking for ones that would be easily mountable to my situation (huge, industrial equipment).· Thanks!
Kelvin, the 2pe Motherboard looks interesting, but I need at least four digital inputs and up to 6 digital outputs, and that doesn't include the encoder (which, as you point out, would be handled by the DVR daughterboard processors).
I wonder if with using the StampPLC with a 2px I would be able to measure 2 sets of pulses, with a minimum pulse width of 1/64 of a second (60 rpm max, = 1 rps, with 64 position encoder).
And I like the PLCStamp because it works with 24 volt source and switch values, but I'll have to find a way to step some 5 volt inputs up to 24v, I guess with some transistors.
Comments
One guy here at the office suggested a gear 3:1 that drove a big fan.· The faster it went the more aire resistance there would be.
Post a sign that clearly indicated the maximum number of passengers at any one time. At the top landing and at the bottom. My guess is that one or two adults until you have things really sorted out. If you are moving heavy stuff, do so without people on board.
It is all too easy after a party to have six people crowd into what you have for a quick ride down. I have doubts that the gear boxes and braking have that all worked out. Cables are quite strong and most likely the least of your worries.
Again, counter weight tremendously improves your safety and control. Steel/cast iron is double the mass of concrete; so it is the most compact cheap counter weight. Concrete and aluminum are nearly the same mass. Ideally, you may be able to have an emergency brake that grabs the counter weight's cable.
Having the twin cables is fairly good. But if the winches are not rated to pull the whole load individually; a failure of one may cascade into a failure of the second. Significant redundancy is the usually primary path to safety. I do realize it is costly, but go the extra distance and have a system that you can fully trust; even when you are not there.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
After looking at your videos I would be concerned about the possiblity of the cart tipping or derailing. Do you have a way to keep the wheels from coming off the track? You would need something that cups the bottom of the track. I assume the supports for the tracks are directly below the center, so your anti-derailment device would have to hang below either side of track with a gap in the middle. This could be part of the braking system as well -- sort of like caliper brakes on a bicyicle.
In the case of both cables failing, the braking action will tend to cause the cart to tip over on the downhill side. It is important that the anti-derailing device prevents this from happening. You could sense the tension of the cables by how much they can be deflected, similar to the way someone tests the tension on a fanbelt by pushing on it. You could build a tension detector that pushes on a normally-open switch. As long as the switch is closed it will energize a solenoid that keeps the brakes open. The brakes will engage if one of the two switches opens, or the circuit loses power, or a wire breaks. I would hang the tension sensors on the cables near the attachment point to the cart. I wouldn't put tension sensors inline with the cable. This would just introduce another possible failure mode.
To me, the possbility of tipping is a bigger issue. If there are four adults on the cart, and everyone leans over the railing at the same time this could produce enough leverage to tip the cart sideways. If everyone leans over the downhill railing the uphill wheels could raise up from the track. The tension on the cables should keep the cart from tipping backwards, but the uphill wheels could derail. You could reduce this possbility by raising the height of your safety rail, but I still think there should be a device to keep the wheels on the track.
Dave Hein
Is it possible to turn it over? Yes, but they would really need to try to do so. It weighs about 200-300 lbs without anyone in it. It is 32 inches wide, and the rails are 30 inches apart on center. When I work on it and try to lift one side to get access to work on a wheel or whatever, I nearly strain my back to lift it. Plus, the uphill portion is angled, to get closer to the cart.
if it does tip over, it would be a somewhat soft landing. Its a forest floor and 2/3 of the way the cart is only 6 inches to 2 feet above the ground.
I can see your point of view tho. The videos look worse then it actually is. Plus, we now have benches on the thing, so stting increases the lower center of gravity.
Thanks.
Jeff
I'm just thinking of some worse case scenarios. I agree, the cart "probably" won't derail. However, if someone wanted to try to tip the cart for fun they could stand outside the railing and lean out. The moment arm of the cart is only 15 inches. Two 175-pound guys could tip the cart if their center of mass was about 13 inches outside of the cart. Of course, a 4-foot fall to soft ground probably won't hurt them, but a 300 pound cart falling on them might sting a bit.
Also, attaching the cable to the back of the cart actually makes it more likely that it will tip backwards when the cart first starts moving. If four 175-pound guys were at the back of the cart its center of mass would be a foot or so in front of the back wheels, and about 5 or 6 feet above the wheels. A quick tug would send it tumbling backwards. The only thing keeping it from tumbling would be the cable pushing against the front of the cart. It would be like pulling the rug out from under someone. If you pull slowly they won't fall, but a quick tug will send them tumbling.
If it were me I would put some sort of postive retention on the wheels to ensure that the cart could never tip or derail.
Dave
Also, I know this will stir debate, but to keep the cables equallay taut, each cable is attached to its side of the cart, and another segment of cable about 6 feet long is attached to each of these cables, and then through two pulleys near the back of the cart. Therefore, the tension is maintained, so if one spool wraps over but the other one doesnt, the 6 foot cable distributes the tension evenly. Some people look at the pulleys and say "ah, if one cable breaks, it will roll through the pulleys and let loose" but thats not the case because each spool dead ends onto the cart, and its only the segment that is on pulleys. I hope I didn't confuse.
Where did you get those buttons? I want some! By "Those Buttons" I mean the buttons on your control box, very professional looking!
worthwhile Part:
Thinking... Thinking... Ok, Here's a plan, Let's assume your place a new rail on the elevator, I'm sure you could rig a device that when the towing lines went lax(Ie, use some type of counter springs to rule our just general taughtness by the shear weight of the lines) a spring loaded brake engaged, but would not engage at the top or bottom because some type of physical barrier would stop that process. I think that might work.
The remote control is actually a small panel that has those buttons wired into a linearcorp remote, which has 4 buttons.· We currently only use 3, but I hope to put a center stopping point, so we may need to add a button to it.
Thanks.· Jeff
We are adding a lower deck area for the cart to stop at (near bottom of the house for firewood etc).· The cart now either goes all up, or all down.· At the bottom of the lift, there's a button to bring the empty cart down, and vise versa at the top.· We do all of this with the motor controller which although it is very powerful, is somewhat limited in conditional processing.
If we have a midpoint stop, I need a way to "call" the cart to the new landing.· I don't want my kids to go through the decision process of "Up" or "Down".· I need one button to bring it, so somehow I need some logical process to decide, to send up, or send down.
Therefore, using a stamp with a Hall Sensor I can determine the RPM for the original problem proposed, as well as determining the location of the cart (there are 42 spool rotations from top to bottom).· If I know the location, via relays I can:
Dad and I have discussed it, and we are going to have a series of relays that will allow us to "switch over" to a stamp solution.· In otherwords, if our stamp fails, we can turn off a switch and it will go back to the current operation which seems to work fairly reliably.
My research has shown that the PLC BS2 panel is the one for me.· The control box already has a 24volt bus.· Now I need to figure out which of the stamps to get, the BS2 at a minimum.
I hope that now I've decided to go with a stamp, I can get as much good help·on my stamp development as I have on other potential solutions!
www.munsonworks.com/munson/products.html
I have seen many of those sites, but hadn't seen that one before.· I liked that cable track design where the cart sits in between.· I can only imagine how much concrete they would need to keep those cables tight.
We initially priced some of those systems, but they wanted close to 30 grand for a complete system (installation not included).· We built ours for under 7k.
It doesn't have a second cable. And it doesn't have a counterweight system.
I still prefer having the counterweight as it really will conserve on your power bill as well as reducing stresses on the primary drive systems to a minimum. In the long run it might actually recover its own costs.
I live in Taiwan and we have many [noparse][[/noparse]likely thousands] of small low tech elevators that rely on a single winch system. The tracks actually lift away from the ground floor to allow auto parking. Many building owners use these as freight elevators to store goods up to 5 floors about a ground store outlet. It seems to work fine as long as the traffic is not intense and the users are aware of the limitations.
Forgive me, but I assumed that this was an main entry point into the home, rather than backyard access. I happened to have a cousin that had a home on a sea cliff which did have such a main entry lift that delightfully ran above a rhodedenron garden as it decended from parking to the main entry.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
Looking at the pics, you could add 4 more wheels to keep the cart from "bouncing" off of the rails;
...T.T.T
....\.l./
S--.O.--S ...."periods are for screen formatting"
..../...\
...B...B
Leaving just the bottom center wheels off for rail support, the two bottom sets would not have to be as tight to rail as well..
Some one liked the switches you used, here is a source for totally waterproof digital ready switches for industrial use.
The technology;
www.itwactivetouch.com/pdf/ITWActiveTouchBro_R1(0806).pdf
The actual switches;
www.itwswitches.com/pdf/activemetal_catalog.pdf
Bob
I'll save that link for other switches should I need them.· The ones I am using are industrial grade and rainproof.·
since this is not part of a main entry, I suspect that you can merely claim it as 'not for passenger use' -- just a 'dumb waiter hoist'.
The should satisfy local buiding inspectors and insurance people.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
Jeff,
The switches are made by C3 Controls in Beaver, PA.
Phone 724-775-7926, fax 724-775-5283.
They are NEMA 4 rated and can be provided with Class 1 Div. 2 explosion proof contacts.
I also have additional reasons now to use a stamp other than the safety issue as discussed above.
Thanks.
Jeff
I wonder if with using the StampPLC with a 2px I would be able to measure 2 sets of pulses, with a minimum pulse width of 1/64 of a second (60 rpm max, = 1 rps, with 64 position encoder).
And I like the PLCStamp because it works with 24 volt source and switch values, but I'll have to find a way to step some 5 volt inputs up to 24v, I guess with some transistors.