Dover Elevator - Hydraulic Pump Shuts Off

Where is the cab now?

First floor covering the pit

You might call these people, http://www.reliantelevator.com/

The pit safety switch would be in the pit underneath, somewhere.

It will be on the pit access gate.

is the elevator on a plc or hard wired?

I am not familiar with the term plc but it is a hard wired permanent installation

The term P.L.C. refers to a 'Programmable Logic Controller' (a more reliable & compact unit for controlling electrical circuits & does away with masses of relays & contactors)

There are many reasons why your hyd pump would shut down, if there is a fault with the pump itself or your trying to run it 'DRY' (without hyd fluid or the correct viscosity) it may overheat. They usually have thermisters fitted internally for temp. safety circuit & often the supply to the pump runs through thermal overload coils which may reset automatically if they are overloaded & trip.

You really need some understanding of the system your working on, in the control panel you should find a row of terminal connections for lift car & shaft wiring, incorporated in these terminals are all the safety circuits for car doors, landing doors, pit safety switch, car safe edge (if fitted) speed govener etc etc. these are all connected 'daisy chain style' & if any of the safety circuits are NOT made the lift WILL NOT RUN.

If you can identify these circuits & check each terminal in turn with a DVM (Digital Volt Meter) you will be able to determin if all safety circuits are in tact.

You could also check the contactor supplying the pump & confirm all 3 phases are Making correctly, if one of the contacts is failing (high resistance) & the pumps trying to run single phase it will pull more current & trip thermal overloads.

hope this is of help to you, let us all know how you get on ??

Best regards Aerotech.

In almost every hydraulic system I've seen, there is a low-pressure switch that will stop the pump on a loss of oil pressure. They are typically delayed from activating for 30 seconds to one minute to allow the pump to start with no pressure. After that time, the low-pressure switch is enabled. If you have a bad pressure switch, then this is what you would see.

Of course, the pump could be bad and you really don't have any pressure. In that case the switch is good any doing its job.

Would cavitation also cause this problem? If the fluid is oxidized, it would be thicker, causing the pump to cavitate. If too much dirt, or water, the same thing could occur.

Why not call Thyssenkrupp? They are the ones who purchased Dover about a decade ago. I have an older traction type Dover elevator here at work that is 47 years old and don't have any issues. 480V 3ph hydraulic sounds much newer than that, and any company that is qualified should be able to diagnose your issue and get it going again.

Do not venture into the pit unless you are certain the car isn't gonna squash you flat. That would be bad. Make a mess. Stain the concrete.......

Call a certified elevator mechanic!

My wife always complains when I come home with blood on my shirt and no Caribou so good chance I will not go into the pit without a rail road tie. This is old stuff and I am thinking bypass all the safety stuff and call it a dumb waiter. I am close to giving up on it.

Do not give up. Why not wait for Joe Moleski to contact you? He has offered to help.

was just curious because you could use your plc software and see whats holding you out if its a sensor of sorts. more that likely it does sound like your pump is low in fluid, high heat, or single phasing. like the fellow said early you cant rule out your pressure swicthes either. also check the ohms between the overloads and through the contactor/starter and the connections in the motor head, they maybe loose.

I don't have plc stuff, I have 60 old relays triggered by old junk, could be sensors driving them or coil failure,the reservoir is not low, the oil is not hot and I have clean 480 3-phase to the panel. This is a control problem I could figure out if I had a good set of schematics and the time to devote to it

Are the relays labelled in any way ?? do you know purpose & function of them ??

Would be beneficial if you can identify lift car push button terminals from the control panel ( then with a piece of shorting wire you can manually select lift car floors from the control panel & watch relays)

Did you manage to identify the terminals for lift & shaft safety circuits ?

1/ check contacts on lift car doors

2/ check contacts on each set of landing doors

3/ check contacts on O/S/G (over speed governer)

4/ is the hydraulic lift :-

A/ a telescopic ram underneath the lift car ?

B/ side mounted with compensator pully mounted on top of the ram & wire rope configuration, with or without counter balance weights ?

5/ check both upper & lower ultimate safety limits.

6/ pit stop switch & landing emergency stop switches (located inside the shaft if fitted)

7/ check travel timers (in control panel)

8/ Does the lift have manual floor selection limit swiches in shaft (usually arm & roller with striking ramp configuration) magnetic tape head system or stainless punched ribon & optical reader ??

Located usually on top of the hydraulic tank is the valve control block, you say when you place a landing call the lift pump starts up & runs initially then stops after a few seconds ?? if you put a metal srew driver shaft next to each valve & detect a magnetic field while the pump runs you'll know if & which valve is energized & operating.

Also don't laugh !! but between the hydraulic tank & lift shaft ram ( located in the pipework ) you will find at least one (maybe 2) hydraulic isolation shut off valves if the lever is inline with pipework valve is open & ready to operate, if lever is at right angles to pipework the valve is closed isolating hyd flow !! do check this. (usually there is a hyd isolation valve immediately after the hyd tank & sometimes one in the lift shaft pit immediately before the hyd. ram)

Waiting with bated breath in anticipation............good luck !!

Some times on the hydraulic valve block (dependant on make & model) they have a manual pump, do you have this facility ?

If so you can manually pump in order to raise the lift car in the shaft, hope your fit though can be hard work !! lol

Also underneath the lift car you should find the guide wheels or rollers that run on the shaft steelwork guides, next to these are 'DOGS' sprung loaded wedge shaped pieces of steel with teeth, these clamp onto the shaft guide rails in emergency, only operate if the lift car is in a downward free fall motion. these operate mechanically (usually with wire rope connected to overspeed governer) if operated can only be released by lift car being hoisted in an upward motion (hence manual hyd pump on valve block) & sometimes they have a manually operated re-set limit switch connected to them, something else you should check.

Regards Aerotech.

Hi,

firstly dover have been obsolete for over a decade and parts are not avaliable.

i am a contracts manager and have to manager 500 social housing lifts. the best thing you can do here is contact a decent lift company. don't waste time with the big four. otis, kone etc. get a specialist company in to remove and replace this lift. you will need a bespoke lift designed for your shaft configuration. the main companies only do new builds and the lift will only last 15 years.

if you do wish to fix the problem. most likely a pressure switch or could be a blocked valve not releasing the fluid. you could also have a phase failure issue with the PFR ether way without a techncian who deals with hydraulics your up the river.

if you do get this working all you will be doing is trying to source parts and getting these specially made up for this lift in the future.

replacement is best as at least you will meet EN81 and DDA standards in lifts and do not have to worry about the safety of passengers using this lift. what does the insurance company advise? as they are the ones who inspect this plant and provide cover?

Good luck.

Dover parts and materials are still widely supported by ThyssenKrupp and the aftermarket. There is nothing on a Dover we can't fix. That said, the case for replacement can be made. However to replace this with most of the Big Four stuff is trading one problem for another unless your specific about the equipment being used. Just returned from a modernization trip in which Schindler is doing a replacement and I spec's nonproprietary controls and they are doing so. The big four can be used effectively, you just have to guide the process. Joe