Ottawa staircase lock - a technical question

[magpie patrick]

I've long been fascinated with the Rideau Canal, although I've never seen it. Looking at pictures of the 8 rise staircase lock in Ottowa (well, we are in lockdown, and I can dream of better days ahead can't I?  ) I noticed that the gates are opened and closed using a winch and rod mechanism, the winch pulls the gate open or pushes it shut via a rod. Whren I get there (one day) I'l have a closer look  ? 

 

But one gate doesn't have the rod in place, and examination of another picture shows there is a building in the way... a canal building no less! It's not some inconsiderate developer. Two questions...

 

how do they get that gate open? 

 

And given it's a canal building, my guess is they wouldn't have messed up their own design, so the gates originally had a different mechanism - what was it?

 

I'd be surprised if anyone on here knows so feel free to speculate!

 

 

[Tim Lewis]

 

[David Mack]

Balance beams?

http://collections.musee-mccord.qc.ca/en/collection/artifacts/MP-0000.25.174

[Wittenham]

I have ice skated on it, but did not pay much attention to the locks.

[magpie patrick]

45 minutes ago, David Mack said:

Balance beams?

http://collections.musee-mccord.qc.ca/en/collection/artifacts/MP-0000.25.174

That would make sense, even with short beams like that a chain could pull the gate open and pull it closed again, which is the function the rods serve as chains can't push!

49 minutes ago, Tim Lewis said:

 

I need to watch that several times and take notes - it is far from being a conventional staircase!

[magpie patrick]

Having watched the video I really must go and see this structure - it is like no other and I had no idea!

 

From the video - locks 1-4, descend in normal staircase fashion

 

Lock 5, only a shallow fall compared to locks 1-4

 

Lock 6 - copings level with lock 5 - much larger fall

 

lock 7, passed on the level but could have held about 3 feet more water

 

Lock 8 - drop to the river - copings level with lock 7

 

So it looks like lock 6 could be filled to mean lock 5 could be passed on the level to lock 4 : edit corrected the copings may be level but the gates are lower, Lock six can not make a level with the top water level of lock 5

 

 and lock 7 was redundant on this occasion but both it and lock 8 could have held another three feet of water  edited again - lock 8 bottom gates lower so it can't hold water to top level of lock 7

 

I've never seen a staircase like it - perhaps because there isn't another one 

Edited April 16, 2020 by magpie patrick

[Captain Pegg]

The lock gate in question has two chain mechanisms which suggests as per all the other gates there is one for opening and one for closing. Logically then perhaps there is a push rod at invert level that can travel beneath the building in a small heading. It could be driven by the outer chain mechanism via a gear. The only difference may be that you probably can’t use both mechanisms to open the gate as the crew of the boat in the time lapse seemed to be doing.

 

JP

[OldGoat]

It's much clearer if you do a google earth with the satwellite and street view option.

The 'towpath' is very narrow on the left - hence the double double chain operation. I wonder whether the flight was built with all balance beams originally?

[magpie patrick]

4 hours ago, OldGoat said:

I wonder whether the flight was built with all balance beams originally?

Well the top gates certainly have!

 

 

Once I'd seen this they can be seen in the video too, but I hadn't been looking for them. David Mack's picture shows similar beams all the way down the flight

 

I really am intrigued by the arrangements at chambers 5,6,7 and 8, counting from the top. In the video the boat goes from chamber 6 to 8 without using chamber 7. Chambers 5 and 6 have their copings level, chambers 7 and 8 also have their copings level, but in both cases the lower chamber has the top beam of the gates lower

 

I wonder what other party tricks these lower chambers can perform, and above all, why? 

[David Mack]

Bottom lock might well have been built with higher walls to cope with varying water levels in the river below.

Doesn't help with locks 5/6 though.

[Scholar Gypsy]

Off topic. I noticed from a recent video (by minimalist) that some of the lock gates on the MSC are opened and shut using chains. The ones that close the gate must lie along the bed of the canal. There are a series of pulleys that bring the chain up to ground level. You can see them at 14:45 or so (lower gates) and 15:25 (upper gates) here