Lifting a manhole cover

[Matty F]

Well it's not really a manhole cover because it's much smaller. But it doesn't seem to have another name. Anyway, after 40 years it had rusted in place. I tried a hacksaw blade around the edges. That worked OK down to about half an inch. But the cover is 3 inches thick down to the ledge. Tried a 4 foot crowbar in the hole, levering in all directions. Tried hitting it a hundred times with a sledge hammer. Tried heating it very hot with a blowtorch. Tried freezing it.

Then I made a 16mm key to fit in the hole, with a ring on top. Tried levering it up with a 6 foot crowbar but the crowbar bent.

Eventually, put a 5 ton jack under the crowbar, and the cover lifted up. I estimate that I applied about a 1 ton force with the jack, and the

4:1 leverage of the crowbar made it about a 4 ton pull to lift the cover. Here is the cover just starting to lift: 've ground the edges of the cover with an angle grinder and put CRC on it!

[Tim W]

Matty F wibbled on Wednesday 30 September 2009 12:38

Why are you fiddling with railway (or tramway) lines - do tell...

[Mit]

For some reason the ones in the street covering water or gascocks are known as Tobys here in Scotland.

The usual technique with a jammed Toby. ;-)

Tim

[Matty F]

I've got the job of devising the mechanism that makes the points flip from one side to the other without stopping in the middle. It involves a spring!

[Matty F]

Thanks, they seem to be called Toby covers here in NZ too. Maybe we have Scottish engineers here!

[Jules]

Heck - I'm surprised it didn't just pull the whole surround out of the ground, too. That sounds seriously jammed...

(rail noticed in the photo too, as Tim did - if the spring idea doesn't work out, maybe some sort of heavy weight that can flip between two positions, moved by a cunning arrangement of levers so it doesn't require much effort?)

cheers

Jules

[Tim W]

Matty F wibbled on Wednesday 30 September 2009 13:49

Cool.

Is it a tram, preserved line or do you work for the mainline railways?

[Matty F]

Well the jack and the crowbar fulcrum are both on the steel that the box is welded on to! I was expecting the 16mm thread on the bolt to strip first.

It's a tram rail. That means that people will drive cars all over it. So we can't have any levers sticking up.

[Matty F]

It's a tramline. There are 8 lines going to trambarns, and each needs the points to be changed when the trams are put away each day.

[Jules]

D'oh, so they are. In my defence, it's still morning here and I'm sick today :-)

I thought they often had a covered channel containing a bar which connected to the points at one end and the operating mechanism (whatever it may be) at the other - but I suppose that is just creating more work if you don't have that already...

[dennis]

Maybe an A frame made out of a couple of rails and a cable to the back of a tram? Something would give.

Next time maybe run an acetylene torch around it like you would with a stuck bolt.

[John]

I can't imagine how you managed to try to freeze it. Quite a lot of mass.

[The Medway Handyman]

Should have used WD40 :-)

[Graeme]

In message , Matty F writes

A Youtube film showing simple points operation :

best not copy their overhead catenary, though :-)

[Tim W]

Graeme wibbled on Wednesday 30 September 2009 21:06

Bloody hell - and you wonder where Scott Adams got his ideas for "Elbonia" from...

However, that roll and tip rig looks pretty smooth. I hope the underground structures are built more like that and not like the points or overhead supply!

Blokes seem happy enough though.

[John]

But why do the carriages look so sad!!

John

[Matty F]

We used Freeze Spray. It didn't do anything useful. At that stage I was unsure of the construction underneath the cover. If I had known there was up to 3 inches of rust I wouldn't have tried most of the techniques.

[Clot]

That was amazing. Thank you. I loved the bit where it looked as if he was making and breaking contact on the catenary so that it sounded more like a steam engine!

[Nick]

Good work that man. Also delighted to see that you are using a Barrett (Duff-Norton type) jack.

I still use these, they are invaluable, but the elfin safety would blow a gasket if they knew of such goings-on.

Around here the utility companies use a metal framed, hydraulically powered gadget to lift a manhole or inspection cover. (1) Takes two men half an hour to erect the kit, put out the signs and cones, put the kettle on. (2) Another half hour to drink tea, have a munch, cigarette and inspect the local hedgerow. (3) Two minutes to lift the lid. (4) If that doesn't work try (2) again (5) Reverse (1)

[Clot]

Once upon a time, I used to have to do that sort of thing. Effing great 'ammer used to sort out most cases. A more effete team thought that such effort was undignified and bought an hydraulic system, (rather like the "tuning fork" hydraulic for lifting out an engine).

I borrowed this brand new piece of kit to assist me on a particularly antisocial lid. Even then, in about 1980, the Elfins were about. I stuck the van with an orange flashing light in front of the M/H and some of them cones that a particular DJ used to be concerned about astern of us.

Within 5 minutes we were cranking the 'andle. Within 7 minutes we had some serious metal spaghetti!