DonsDeals Blog: Home Made Hydraulic Elevator

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Sunday, April 1, 2012

Home Made Hydraulic Elevator

Video Link...
http://vimeo.com/37793506

Home Made Elevator

Michael Ruppe

Home

Question: What do you call a forklift ram, three-phase motor and pump, a small shed and some latching relays?
Answer: A home-baked elevator.

Above: The entrance door opened showing the sliding cage door and Kevin's various knick-knacks.

Above: Inside the elevator looking to the left we can see the hydraulic ram and lifting chains.

Above: All hidden nicely behind an access door.

Prologue: In mid-2011, an elderly man approached me at work with a schematic provided to him by an 'electrician'. Sadly for him, the circuit he built from the diagram did not operate. The schematic in question proved to have an elementary error. After working out the error together he left the store and returned the next day satisfied with some marginal progress in his project.
The project in question was a hydraulic elevator. With the backbone being a forklift ram, a three-phase motor powered the hydraulic pump which would raise the elevator through the shaft. A single phase powered release valve allowed the elevator to lower. When the valve is actuated, the elevator's downward pressure pushes the fluid back to the reservoir. In this way, the resistance of the fluid passing through the valve provides the necessary pressure to slowly lower the elevator cab through the shaft. in other words, the descent is powered only by gravity and regulated by the viscosity of the hydraulic fluid.

Above: The pump assembly showing the motor, (the protruding cylinder on the upper left of the assembly) the release valve (right of the motor) and the large reservoir. The pump itself is a fully immersed pump and as such is hidden inside the reservoir.
Kevin had spent 15 years in hydraulics and has experience in construction. He was comfortable casting a hydraulic ram into his basement slab and wiring in three-phase mains for the lifting pump. But when it came to DC circuitry he was completely at a loss. You see, Kevin had to convert the control systems of this elevator to 12V DC in order to receive certification on the unit. No certifying authority would even look at the elevator system while the cab had mains power lurking behind the control buttons.

Seeing his dilemma, I offered assistance. After describing to me as best he could the system, I completely ruled out a microcontroller driven system. I put together a prototype controller board along with wiring connection diagram. The prototype consisted of two latching relays which would control the three phase pump assembly to raise the lift, and a release solenoid to lower the lift. Reaching the limits of the shaft would actuate industrial micro-switches to reset the state of the latching relays.

I visited Kevin in early December 2011 to help him out with wiring my control board into his network of 12v DC switches, buttons, led's, microswitches and electromagnetic door strikes. I arrived at Kevin's at 9:30AM. I was driving back home at around 10:30PM. The day was spent first comprehending the system; Going up is powered by a three phase motor and hydraulic pump. Going down however is a single phase hydraulic solenoid that opens to allow fluid to return to reservoir – the cab just coasts down slowly as the fluid is pushed back to reservoir. The following hours were installing my control board, chasing cables, simulating rides based off the state of the relays, faults, power outages, and general, potentially property damaging mishaps like pressing the up button when you're already at the top of the shaft. Tinkering with various wiring harnesses, getting the top and bottom exterior doors to lock and unlock at appropriate times.

Above: The first prototype of the elevator controller. The blue terminals down the bottom are all the inputs from the control switches and user buttons. The top two pairs of blue headers are the outputs for up and down. With only two storeys in the house, the whole board is electrically very simple.

Read More...
http://michaelruppe.com/home_made_elevator.html

I like the simplicity of the build. The use of the Fork Lift Ram and the relays and micro-switches instead of a micro controller. Lets face it... micro controllers can be blown by the slightest Voltage Spike and often get killed by Lightning Storms. I lost 2 TV's, 2 HD Tuners and a Router in one Storm. And they were all on Protected Circuits. One of the TV's had inline RF Protection in the Cable. The other one didn't, but it made no difference. It was obvious that the Spike came down the Electrical Line and not the RF Cable (RF is coming from the TV Antenna, which is Grounded to an Earth Ground). I figured out that the Spike cam down the Electrical Line. Because, the Router was not connected to the RF Cable and it was Damaged at the same time as the TV's and Tuners. One TV and Tuner was Dead. And on the others. The Electronics were just Damaged and never worked right again. Lightning can Jump most Protection Circuits anyway... The House was not Damaged and we would not have known, exactly what happened. If it had not been for a Neighbor (across the street) who saw the Lightning Flash between ours and our next door neighbors house. It was not even raining. Just partly cloudy and some Thunder. And of course, that one Big Lightning Flash!:O Besides all that... I like this build. Because, I use to do Car Wash and Gas Station Maintenance, back in 1976. And I'm familiar with those Hydraulic Pumps, 2 and 3 Phase Motors and Relay Switches. That's right up my alley;)

Don