Now this is what you call a gear box

mickoo

Western Thunderer
Part of this weeks work was to assist in replacing a main hoist gearbox (the last one went bang big style!), it's too big and heavy to go up in one piece so the lid went first, then the input and output shafts individually and finally the base with intermediate shafts. On the right is the input shaft with brake discs at just over 1m in dia, on the left the output shaft with couplings to the two hoist drums. Power is two 500Kw motors so just about 1Megawatt of power, about the same power usage as 100-150 houses at tea time, however when lowering we use regenerative braking and pump back about 7-800Kw. Max lift is 100 tons.
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Dog Star

Western Thunderer
Given the loads to be lifted and the power available at the input shafts then there is going to be a fair degree of thrust along the shafts because of those helicals - what takes the thrust? Or does the change in tooth angle on the driving gear, between shafts, minimise sufficiently the side thrust?
 

mickoo

Western Thunderer
The I think the bearings are all flat roller bearings I.E. not thrust bearings so presume the gear angles must counter any such thrusts, but I can check on Monday, I'd of taken a photo of the one that failed on the last gearbox, but it was just a pile of metal bits in the bottom of a bucket :eek: The shaft was so damaged it'll need metal spraying and skimming (that's a clever process if you ever get to see it), not sure what they will do with the housing as it's cast, though to be fair the scouring was pretty light, but being a casting it may well be junked or the bearing seat may be opened out and a sleeve heat shrunk onto the new bearing to make up the gap.

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There's something quite special about shiny machined metal I think.

Steph, no idea on price but I can find out on Monday, I think we hold two of these as spares in our stores, as well as several others for other different cranes, I think our stores runs at around £15-18 million stock levels. We've just ordered three new cranes and got them cheap at £8 million each, cheap because they were already ordered and part built when the original buyers dropped out and being part built we get them in just under a year, normally it's about three years from contract signing to end of commissioning and working the first vessel.

I'll grab some in situ shots on Monday, it's very difficult to get a scale of just how big all this kit is.
 
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Osgood

Western Thunderer
Guess 1) double row ball
Guess2) spherical roller
Guess 3) double row ball/spherical roller at small gear end of shaft, roller at big gear end
 

oldravendale

Western Thunderer
Mick - what happens when that gaily coloured rockaboogee bit of rag gets caught up in the works and blocks an oil channel?:D

Actually, I suspect nothing with gears of that size.....

B
 

mickoo

Western Thunderer
Mick - what happens when that gaily coloured rockaboogee bit of rag gets caught up in the works and blocks an oil channel?:D

Actually, I suspect nothing with gears of that size.....

B
I've no idea, but I did have a little snigger at the cryptic note on one end, and yes, apparently some one didn't recently :cool:, and no, it wasn't me ;)

IMG_5545a.JPG

There are no oil channels as such, it's a splash lubricated box, the oil level being up to that little round sight glass above the drain tap and just below the upper and lower casing joint, all I know is that it's more than 100 gallons, coz they used up two 50 gal drums and then went for some more.
 

Ressaldar

Western Thunderer
.....and presumably they are 'handed' with the 'IPS' (Ipswich?) chalk mark on the flange in post #1 so that it faces the right way when fitted?

cheers

Mike
 

mickoo

Western Thunderer
.....and presumably they are 'handed' with the 'IPS' (Ipswich?) chalk mark on the flange in post #1 so that it faces the right way when fitted?

cheers

Mike
Exactly, though you can't get it the wrong way round due to the motor and drum layout, but you can get the brake discs and couplings wrong, so the IPS is not a facing direction but is the brake disc and splines to fit the other half already attached to the motor, you can see the same on the coupling on the left, it's also marked IPS to mate up with it's respective drum. The other side are marked FEL, not also the white alignment line on the drum couplings, the drums are dogged off so cannot move for alignment, thus the couplings have to back exactly as they came off and in alignment with each other. The motor shafts can be rotated to line up with the discs in situ.

When the gearbox arrives it only has plain shafts, the couplings and brakes have to be pulled off the old one and fitted to the new gearbox before it can be installed. Once the gearbox is in place then both drums and both motors will have to be laser aligned to ensure as straight a drive as possible, especially at these weights.
 
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JimG

Western Thunderer
When the gearbox arrives it only has plain shafts, the couplings and brakes have to be pulled off the old one and fitted to the new gearbox before it can be installed.

That might be fun. :) My father was the chief electrician at the large whisky distillery in our town and there were a few large motors in the 150 - 200HP range in the plant and getting pulleys and couplings off was not an easy job - usually done with a very large hydraulic puller, oxy-acetylene torches for heat, and a lot of cursing. :)
:)

Jim.
 
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