The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet. I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

Just remember this is a for a 'dumbwaiter' not an elevator, I don't want
the nanny's out there panicing about giving advice or suggestions for an
elevator and I'm not looking for designs just an idea how I might go about
making a pawl that can be disengaged by raising a platform higher. I just
want to add as many layers of protection as I can.

I've got some general designs on paper and as soon as I flesh it out a bit
more I'll start crunching numbers for loading and stress for beem sizing
and such. I plan on over building the 'dumbwaiter' but not stupidly
overbuilding it

Bill

Bill wrote:

The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet. I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

Just remember this is a for a 'dumbwaiter' not an elevator, I don't want
the nanny's out there panicing about giving advice or suggestions for an
elevator and I'm not looking for designs just an idea how I might go about
making a pawl that can be disengaged by raising a platform higher. I just
want to add as many layers of protection as I can.

I've got some general designs on paper and as soon as I flesh it out a bit
more I'll start crunching numbers for loading and stress for beem sizing
and such. I plan on over building the 'dumbwaiter' but not stupidly
overbuilding it

Bill

Get a Harbor freight cable hoist and make a suitable basket for it to
lift. A hoist with a hook isn't an elevator nor is a cargo basket to be
picked up by that hook. Lift the basket above the second floor deck
height and pull it in with a hook-pole as you lower it back to the deck.

Bill wrote:
The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet. I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

Just remember this is a for a 'dumbwaiter' not an elevator, I don't want
the nanny's out there panicing about giving advice or suggestions for an
elevator and I'm not looking for designs just an idea how I might go about
making a pawl that can be disengaged by raising a platform higher. I just
want to add as many layers of protection as I can.

I've got some general designs on paper and as soon as I flesh it out a bit
more I'll start crunching numbers for loading and stress for beem sizing
and such. I plan on over building the 'dumbwaiter' but not stupidly
overbuilding it

Bill

Sounds like the pawls they have on many auto lifts. Basically an over
center cam pawl. When the lift passes them they rotate up and when it
clears they drop back. To retract them the lift I have has a simple bar
that has pins that engage slots on these pawls. Pull the release cable
and raise the lift and they retract.

--
Steve W.
Near Cooperstown, New York

Life is not like a box of chocolates
it's more like a jar of jalapenos-
what you do today could burn your ass tomorrow!

Get a Harbor freight cable hoist and make a suitable basket for it to
lift. A hoist with a hook isn't an elevator nor is a cargo basket to be
picked up by that hook. Lift the basket above the second floor deck
height and pull it in with a hook-pole as you lower it back to the deck.


I've had a cable hoist dumb waiter to raise firewood from the basement to
the living room fireplace for 17 years. Work well. inexpensive and easy to
constuct. capacity here is 500 lbs.

a step up. I've used a chain hoist to lower apple bins into the packing line
for 22 years. capacity here is 1000 lbs. You can easily get an even larger
unit.

Karl

On May 19, 11:29 am, Bill wrote:

This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it,

Bill

If slicing off you arms is all you are worried about, how about
putting a hinged door on the box that swings out over the second floor
so the box can't go down unless the hinges shear off, then use beefy
hinges? or how about having a cam or some sort of linkage on a door to
the shaft that locks the box in place when the door is open?
Or how about a variation of Elisha Otis' design where the pressure of
the lifting mechanism keeps the pawls disengaged? though a slow leak
would be like a normal decent and could still trap an arm so maybe
that isn't really what you want.
While it might seem that a double acting cylinder isn't needed on a
dumbwaiter, If you do use a double acting cyl, and lock valves at the
cylinder ports (at least for down) it will take a pretty catastrophic
failure to be a big problem, you know, you could use a variation on
that idea, with a sequencing valve and a small cylinder to disengage
the pawl.

Karl Townsend wrote:

Get a Harbor freight cable hoist and make a suitable basket for it to
lift. A hoist with a hook isn't an elevator nor is a cargo basket to be
picked up by that hook. Lift the basket above the second floor deck
height and pull it in with a hook-pole as you lower it back to the deck.

I've had a cable hoist dumb waiter to raise firewood from the basement to
the living room fireplace for 17 years. Work well. inexpensive and easy to
constuct. capacity here is 500 lbs.

a step up. I've used a chain hoist to lower apple bins into the packing line
for 22 years. capacity here is 1000 lbs. You can easily get an even larger
unit.

Karl

Harbor Freight has useable AC powered cable hoists quite cheap and
frequently on sale.

http://www.harborfreight.com/cpi/cta...emnumber=44006

http://www.harborfreight.com/cpi/cta...temnumber=2954

They also have a swing arm for the smaller hoist which would be perfect
for the barn application.

http://www.harborfreight.com/cpi/cta...emnumber=46980

~$135 + tax / shipping, and whatever small cost for a load basket.

Check out an extension ladder.


"Steve W." wrote in message
...
Bill wrote:
The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking
up stairs is getting harder so I've been kicking plans around and want to
see if anyone could help with a detail I haven't worked out yet. I'd
like to make it that the 'dumbwaiter' gets locked in place when on the
second floor, was thinking of something like pawls on the guide tracks
that the carriage would click by so if the 'dumbwaiters' hydraulics would
fail then there would be no way for it to fall. This way if you are
loading a couple of hundred pounds on it it can't suddenly drop taking
your arms, legs or feet with it, although since I'm planning on
hydraulics it would take a really big failure of the cylinder to get that
fast a drop. What I'd like to do is make it that the 'dumbwaiter' would
have to be raised a few inches before going down to disengage the pawls
but I'm not sure how to go about designing it to do this. I could do it
with a solenoid but I think that adds another failure point and would
rather have it be all mechanical in nature. I'm not worried about a
failure while ascending or decending since the failure mode would be a
slow descent as the fluids bleed out, so I don't need pawls all the way
up the guide rails just at the 2nd floor. Anyone ever seen something
like this and could point me in the right direction?? Just remember this
is a for a 'dumbwaiter' not an elevator, I don't want the nanny's out
there panicing about giving advice or suggestions for an elevator and I'm
not looking for designs just an idea how I might go about making a pawl
that can be disengaged by raising a platform higher. I just want to add
as many layers of protection as I can.

I've got some general designs on paper and as soon as I flesh it out a
bit more I'll start crunching numbers for loading and stress for beem
sizing and such. I plan on over building the 'dumbwaiter' but not
stupidly overbuilding it

Bill

Sounds like the pawls they have on many auto lifts. Basically an over
center cam pawl. When the lift passes them they rotate up and when it
clears they drop back. To retract them the lift I have has a simple bar
that has pins that engage slots on these pawls. Pull the release cable and
raise the lift and they retract.

--
Steve W.
Near Cooperstown, New York

Life is not like a box of chocolates
it's more like a jar of jalapenos-
what you do today could burn your ass tomorrow!

On Mon, 19 May 2008 13:29:47 -0500, with neither quill nor qualm, Bill
quickly quoth:

The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet. I'd like to

http://www.theatticlift.com/
http://www.spaceliftproducts.com/pro...celift6000.php
http://www.theatticliftking.com/
http://www.butlersbuddy.com/standard.htm
http://www.butlersbuddy.com/custom.htm
http://www.summitdumbwaiters.com/dum...r-drawings.htm

These might give you some ideas, Bill.


-
Press HERE to arm. (Release to detonate.)
-----------

I've got some general designs on paper and as soon as I flesh it out a bit
more I'll start crunching numbers for loading and stress for beem sizing
and such. I plan on over building the 'dumbwaiter' but not stupidly
overbuilding it

Bill

Mr Otis figured out a safe simple mechanical solution:
http://video.google.com.au/videosear...en&sitesearch=

or type: secret life lift
in Google Video, to get full 24min version or 3 smaller versions.

The inherent safety of hydraulic lifts is also demonstrated.

Jordan

Bill wrote:
The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet. I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

Put the moving part on the track, the dumbwaiter carriage lifts them as
it passes, If the dumbwaiter side is c-channel, when they pass the top
flange a limit switch fires a lamp and you stop and lower to lock. To
lower the dumbwaiter, go up until they fall free, then roll down right
over them.

I saw a very interesting dumbwaiter design once that used a hose sitting
on the top of the lifting rail, a wheel pair around the track squeezed
the hose flat, as water or air was added to the bottom of the hose, it
inflated it, forcing the wheel to roll up the rail.

Stuart

Bob Meyer wrote:
Check out an extension ladder.

You beat me to it. :-)
...lew...

On Mon, 19 May 2008 13:29:47 -0500, Bill wrote:

The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking
up stairs is getting harder so I've been kicking plans around and want
to see if anyone could help with a detail I haven't worked out yet. I'd
like to make it that the 'dumbwaiter' gets locked in place when on the
second floor, was thinking of something like pawls on the guide tracks
that the carriage would click by so if the 'dumbwaiters' hydraulics
would fail then there would be no way for it to fall. This way if you
are loading a couple of hundred pounds on it it can't suddenly drop
taking your arms, legs or feet with it, although since I'm planning on
hydraulics it would take a really big failure of the cylinder to get
that fast a drop. What I'd like to do is make it that the 'dumbwaiter'
would have to be raised a few inches before going down to disengage the
pawls but I'm not sure how to go about designing it to do this. I could
do it with a solenoid but I think that adds another failure point and
would rather have it be all mechanical in nature. I'm not worried about
a failure while ascending or decending since the failure mode would be a
slow descent as the fluids bleed out, so I don't need pawls all the way
up the guide rails just at the 2nd floor. Anyone ever seen something
like this and could point me in the right direction??

Just remember this is a for a 'dumbwaiter' not an elevator, I don't want
the nanny's out there panicing about giving advice or suggestions for an
elevator and I'm not looking for designs just an idea how I might go
about making a pawl that can be disengaged by raising a platform higher.
I just want to add as many layers of protection as I can.

I've got some general designs on paper and as soon as I flesh it out a
bit more I'll start crunching numbers for loading and stress for beem
sizing and such. I plan on over building the 'dumbwaiter' but not
stupidly overbuilding it

Bill

Take a look at the pawls on an extension ladder -- it seems to me that
such a design (or a pair of them ripped off of an old ladder) would work
just fine.

Having said that, I think I'd take the suggestions to use a cable hoist.
Why do something fancy when something simple will do just fine?

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

Harbor Freight has useable AC powered cable hoists quite cheap and
frequently on sale.

http://www.harborfreight.com/cpi/cta...emnumber=44006

http://www.harborfreight.com/cpi/cta...temnumber=2954

They also have a swing arm for the smaller hoist which would be perfect
for the barn application.

http://www.harborfreight.com/cpi/cta...emnumber=46980

~$135 + tax / shipping, and whatever small cost for a load basket.


Place I used to work at had a metal basket restrained by 4 vertical RHS
members. It had PVC or nylon runner wheels on each corner to locate /
restrain the basket. Lift provided by electric chain block. Worked well and
was passed by OH&S inspectors. it had gates with interlocks at ground level
and first floor.

Bill wrote in
. 97.142:

I guess I was too smart for my own good I was trying to avoid the
official use of the word elevator so I was using the word dumbwaiter in
quotes to try to get my point across. There have been a few discussions
in the past about home elevators and mostly what came across was the
belief that no one but a 'professional' engineer should consider
designing one and people were derided for suggesting that they were going
to do it.

The 'dumbwaiter' in question will be 3 foot by 3 foot, 7 foot high and
have a carrying capacity of 500 pounds. (Nuddge, nuddge, wink, wink, say
no more, say no more....)

Most of the problems that people had with the idea of a home made
elevator was of using a winch to move the carriage up and down. None of
the designs had a good failure mode or means of stopping the carriage
from dropping 8 feet or so either with someone in it or the drop
happening when someone would be entering the carriage.

Since I'll be using a hydraulic cylinder to do the lifting I'm
eliminating the majority of that problem, hydraulics having a 'soft'
failure basically just lowering the carriage slowly if there would be a
pump failure, control failure or hose failure. What I'd like to do is
add an additional layer of safety in that I'd like to make it impossible
for the carriage to fall at all when on the upper floor even if the
entire bottom of the cylinder would be sheared off (for the life of me I
can't figure out how this would happen but....)

I've been thinking about it a bit more and I'm leaning toward something
like this.

The carriage comes up past a spring loaded pawl that is pushed out of the
way until the carriage gets past, then it snaps down again in a locked
position where the carriage cannot drop past but whould rest on the pawl.
To get the carriage down the system would have to raise the carriage up
an inch or so where to of the carriage would push against a lever that
would unlock the pawls and allow them to swing down. Once the pawls are
unlocked the carriage could be lowered past them to the ground reseting
the locking mechanism for the next lift. With it all mechanical I wont
have to worry about relays or solenoids or other complicated systems
failing and as long as we inspect the unit a few times a year I wouldn't
be worried about wear and tear negating the safety feature.

Now I just have to design it


Bill

For what you're doing I'd buy a fork lift mast. Just put elevator car on
forks. Bolted on, of course. Get a small electric hydraulic pump to run it.

For a safety from dropping; have you ever seen the catch on a car air bumper
lift? The unit won't go down unless you hold the lever down against spring
pressure. It's just a catch dog that will grab every inch or so.

Just a couple ideas.

Karl

In article 42,
Bill wrote:

Most of the problems that people had with the idea of a home made
elevator was of using a winch to move the carriage up and down. None of
the designs had a good failure mode or means of stopping the carriage
from dropping 8 feet or so either with someone in it or the drop
happening when someone would be entering the carriage.

Why not have the operating switch inside the dumbwaiter mounted on a
bolt that locks the carriage to the rail by a spring? Pull the bolt out
and the carriage moves, release it and it stops at the next bolthole.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

On Mon, 19 May 2008 13:29:47 -0500, Bill wrote:

The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet.

What, you have a barn with *stairs*? What kind of decadent luxury is
that? My barn has (very old, highly worn) 2x4s nailed to the studs,
serving as a ladder. When you get to the top, there really isn't much
to grab onto for the last step.

I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

I'm planning a similar application to get items up to the upper story
of my garage (there's a deck there). I'm going to use a hoist, as
others suggested, and want the "carriage" to remain up top normally,
so as to fill the hole. I plan on manually inserting pins through the
deck's floor joists into matching holes in the lower carriage. It
won't be really convenient, but the dumbwaiter will see only
occasional use.

My bigger issue is what to use to guide the carriage, so it won't
swing or twist during its transit. One guy (whose name actually is
Guy) suggested rails & rollers for a garage door, but I found a linear
slide on a piece of scrapped equipment that has a rail long enough to
work, so that's what I'm contemplating using. It's pretty hefty,
though, and we wonder about its appearance. It also weighs a couple
hundred pounds or more.

[snip]

Joe

On Tue, 20 May 2008 07:48:07 -0500, Bill wrote:

Bill wrote in
.97.142:

I guess I was too smart for my own good I was trying to avoid the
official use of the word elevator so I was using the word dumbwaiter in
quotes to try to get my point across. There have been a few discussions
in the past about home elevators and mostly what came across was the
belief that no one but a 'professional' engineer should consider
designing one and people were derided for suggesting that they were going
to do it.

The 'dumbwaiter' in question will be 3 foot by 3 foot, 7 foot high and
have a carrying capacity of 500 pounds. (Nuddge, nuddge, wink, wink, say
no more, say no more....)

Most of the problems that people had with the idea of a home made
elevator was of using a winch to move the carriage up and down. None of
the designs had a good failure mode or means of stopping the carriage
from dropping 8 feet or so either with someone in it or the drop
happening when someone would be entering the carriage.

Since I'll be using a hydraulic cylinder to do the lifting I'm
eliminating the majority of that problem, hydraulics having a 'soft'
failure basically just lowering the carriage slowly if there would be a
pump failure, control failure or hose failure. What I'd like to do is
add an additional layer of safety in that I'd like to make it impossible
for the carriage to fall at all when on the upper floor even if the
entire bottom of the cylinder would be sheared off (for the life of me I
can't figure out how this would happen but....)

I've been thinking about it a bit more and I'm leaning toward something
like this.

The carriage comes up past a spring loaded pawl that is pushed out of the
way until the carriage gets past, then it snaps down again in a locked
position where the carriage cannot drop past but whould rest on the pawl.
To get the carriage down the system would have to raise the carriage up
an inch or so where to of the carriage would push against a lever that
would unlock the pawls and allow them to swing down. Once the pawls are
unlocked the carriage could be lowered past them to the ground reseting
the locking mechanism for the next lift. With it all mechanical I wont
have to worry about relays or solenoids or other complicated systems
failing and as long as we inspect the unit a few times a year I wouldn't
be worried about wear and tear negating the safety feature.

Now I just have to design it


Bill

I used to work at a plant that had a hydraulic freight elevator,
cylinder was under the car, not telescopic either, went 3 stories
straight down. As far as I was told the only safety there was, was an
orifice in the bottom of the cylinder, if the line broke the elevator
would fall at a normal rate since that was the smallest restrictor in
the hydraulic system. BTW it was a 12,000 # elevator.

Thank You,
Randy

Remove 333 from email address to reply.

On Wed, 21 May 2008 09:28:33 -0500, Randy wrote:



Bill

I used to work at a plant that had a hydraulic freight elevator,
cylinder was under the car, not telescopic either, went 3 stories
straight down. As far as I was told the only safety there was, was an
orifice in the bottom of the cylinder, if the line broke the elevator
would fall at a normal rate since that was the smallest restrictor in
the hydraulic system. BTW it was a 12,000 # elevator.

Thank You,
Randy

Remove 333 from email address to reply.


Known as a "hydraulic fuse" in the trade.