Fun one trolley. 1

[itsmoked]

Here's an odd one. I need to move a 2000 pound (payload) trolley up a 200 foot 17º grade in about 2 minutes. The track is curved.... So I'm thinking DC. Battery powered. Needs about 5 or 6hp.

The batteries are going to add significantly to the 2000lb payload.

I'm looking for any comments or anecdotes on this subject you folks might have.

Your thoughts on hydraulic drive verses gear chain. I need to consider the down slope here too! The hydraulic would provide speed limiting easily.

Motor supplier suggestions? Voltage 24V? 48? 90?



Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

Grade is usually measured in percent (10' rise in 100' horizontal is 10%). So do you actually mean 17 degrees or percent?
Hydraulic systems are not very energy efficient so I don't think that would be a good choice for a high power battery application. To me this sounds like a perfect application for a DC motor. That way you can use regeneration for braking and energy recovery. At 5 hp you probably want to use a standard 180 vdc motor and simply hook enough batteries in series to get your voltage.

 

[itsmoked]

Grade is usually measured in percent (10' rise in 100' horizontal is 10%). So do you actually mean 17 degrees or percent?

Hmmm. Good point. That would be a 31% grade. I was told degrees. I'll confirm that.

Hydraulic systems are not very energy efficient so I don't think that would be a good choice for a high power battery application. To me this sounds like a perfect application for a DC motor. That way you can use regeneration for braking and energy recovery.

Efficiency was my first thought too, but then what happens if a fuse blows on the way down? With hydraulics you can be limited by an orifice. Perhaps, an electric brake?

At 5 hp you probably want to use a standard 180 vdc motor and simply hook enough batteries in series to get your voltage.

Hadn't thought of 180V.
15 lead acid batteries.. Wow.

I can't think of a good way to feed AC to a curved track. If it was straight, I'd just use some sort of coiled or reeled lead.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[davidbeach]

The rails to the wheels make a perfectly good power delivery system. Third rail with return through the the running rails is more common. Look at some of the airport trams, they have a three-phase sliding contact rather than a single third rail. No need for batteries.

 

[waross]

A DC supply via a third rail, an on-board inverter and standard AC induction motors may work well. Normal braking would be by regeneration with spring applied brakes for parking and in the event that the third rail connection is lost.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[MikeHalloran]

Friction of wheel on rail, or wheel and tire on any surface, is not going to get you up that grade. Whether the winch is stationary or mobile, 200 feet of wire rope can be tough to roll up reliably. You could use a funicular, cable with counterweight, but cable is practical only if the lateral curve is very limited.

So, you need a rack railway.

The rack gives you the option of dropping a sprag for emergencies.

You need to wrap something partially around the railhead so the pressure angle of the rack can't separate the rack and the pinion. All the design issues were worked out more than a century ago.

It's time to visit a rack railway, schmooze the staff, and take a lot of pictures.

Bridge cranes use sliding contacts on a partially enclosed conductor bar, typically 3 phases plus ground. I haven't seen it done, but I'd guess the conductor bars could be warped around a gentle curve.
See, e.g., the Insul-8 product on this page:

http://www.conductix.us/en/products/conductor-bar-systems

Mike Halloran
Pembroke Pines, FL, USA

 

[Compositepro]

For a 200 ft run, using a steel winch cable from the top of the hill does seem the best solution.

 

[itsmoked]

The rails to the wheels make a perfectly good power delivery system. Third rail with return through the the running rails is more common. Look at some of the airport trams, they have a three-phase sliding contact rather than a single third rail. No need for batteries.

I like that idea. This is for a residence so 3ph is not probably an option.

A DC supply via a third rail, an on-board inverter and standard AC induction motors may work well. Normal braking would be by regeneration with spring applied brakes for parking and in the event that the third rail connection is lost.

I'd love to use a VFD as the power control. That would be sweet. 5 or 6hp on single phase. Erk!

Friction of wheel on rail, or wheel and tire on any surface, is not going to get you up that grade. Whether the winch is stationary or mobile, 200 feet of wire rope can be tough to roll up reliably. You could use a funicular, cable with counterweight, but cable is practical only if the lateral curve is very limited.

So, you need a rack railway.

The rack gives you the option of dropping a sprag for emergencies.

You need to wrap something partially around the railhead so the pressure angle of the rack can't separate the rack and the pinion. All the design issues were worked out more than a century ago.

It's time to visit a rack railway, schmooze the staff, and take a lot of pictures.

Bridge cranes use sliding contacts on a partially enclosed conductor bar, typically 3 phases plus ground. I haven't seen it done, but I'd guess the conductor bars could be warped around a gentle curve.
See, e.g., the Insul-8 product on this page:

http://www.conductix.us/en/products/conductor-bar-...

Great info Mike! Thanks for the link too. Yes, a gear rail of some sort will be needed for either 17° or 17%. I'll be talking with them directly later today and I can get more definitive info.

For a 200 ft run, using a steel winch cable from the top of the hill does seem the best solution.

I would totally agree. Including a nice counter weight, except for the curve in the path, which pretty much sinks a cable/winch method.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Consider idler pulleys or, if the winch is on-board, hooks between the rails to control the cable on the curves.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[cranky108]

http://www.cograilway.com/Colorado Trains.htm

Or look up electric trains for examples. Although I don't know of any one who has used electric and cog at the same time.

 

[davidbeach]

The Swiss have electric cog railways. Logging operations in the early 20th century used cable/wench over some pretty adverse terrain, including around curves with track side sheaves to guide the cable. There would also be sheaves between the rails and the occasional overhead hold down sheave. It's all been done before if you can just find the right examples. There were lots of examples of these "inclines" in the Sierra's, all gone now.

 

[cranky108]

http://en.wikipedia.org/wiki/Cable_car_(railway)

I usually don't recommend this site, but now and then they do a little explaining.

 

[OperaHouse]

Years back a friend of mine bought a futuristic train from an amusement park, a couple engines and about 20 cars. The park had scrapped the track earlier along with the insulated 3 phase crane buss. I was invited to a meeting of how to get this thing going again. Just the electric buss was going to cost about $150K. I told them to just buy a propane generator and put it in the cab. They didn't like it. The project was tabled for a few years and then another friend was tasked with building the track. At a meeting he was told their electrician came up with the idea of putting a generator in the cab. He reminded them that I had come up with that idea 5 years earlier.

A generator may not be as bad as you think for this project.

 

[controlsdude]

why don't you just take a trip to san fran and look how the trolleys there do it? Just write it off as a business trip.

 

[davidbeach]

That wouldn't be the trolleys, that would be the cable cars. They require a very knowledgable and skilled (not to mention incredibly fit) Grip to get them up and down the hills. Great idea if you want lots of cars on a single rope, making independent stops but far too complex for a single car only stopping at the ends of the line.

Consider a four railed track, a low slung counterweight car riding the inner pair of rails with the payload car riding to outer pair of rails and able to pass over the counterweight car. One rope, balanced for half the projected load, like an elevator tilted over on its side. Remember, an empty elevator cab (traction, not hydraulic) requires power to decend and regenerates when ascending.

 

[sibeen]

What about an overhead feed line as trams use?

 

[LionelHutz]

Is the grade of the track equal all the way or does it vary as it goes up the hill? Is this curve one direction?

If you answer yes to the above then I'm really liking David's idea of using 4 tracks and a counterweight trolly. Keep the cable connection low and beside the inside track for each trolly and let the inside curve of the track guide the cable around the curve.

 

[itsmoked]

Great stuff here! The grade is pretty uniform and 17°(31%). Curve is one direction.

I also think I'm not going to have anything to do with it as the lead guy seems to "have it all figured out".

Just so you all know - it's a wine cellar..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MikeHalloran]

Yeah, let the expert do it.

Jostling the wrong bottle could get ugly.

If you get forced into it anyway, I would amend my earlier suggestion somewhat.
Instead of a cheap rack comprising a pair of angles with sleeves and bolts between them and engaged by a sprocket,
I'd use real gear rack and engage it with a worm pinion. That requires mounting the motor at an odd angle (basically the helix angle), it will drive smoothly enough to not bother the wine. You can probably get away with bending the rack around a gentle curve.





Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Nice idea Mike. Done right, would that also provide the safety of not moving without power? A wee bit of drag is added on the worm side?

Keith Cress
kcress -

http://www.flaminsystems.com