The Peterborough Hydraulic Liftlock was constructed between 1896 and 1904 as a part of the Trent Canal. This canal was completed to provide another route for the shipment of grain to Britain.
The advantage of a liftlock is that a boat can be raised much higher in a specific time than in a conventional lock, as well as allowing travel in both vertical directions at the same time. A liftlock is, however, more expensive to construct than an equivalent number of conventional locks and is only practical in cases of large elevation differences in short distances.
The Peterborough hydraulic liftlock consists of two large caissons supported by rams that are connected by a closed hydraulic system. The upper caisson is stopped one foot below the level of the upper canal. This gives the upper caisson an extra foot of water or an extra 144 tons in weight, over the lower caisson. When a valve is opened, the heavier upper caisson descends, forcing the lighter lower caisson upward in an equal and opposite movement.
On the 245 mile Trent-Severn Waterway, the Peterborough liftlock is one of two liftlocks in the system. In 1896, the Federal Government sent Mr. R.B. Rogers, Superintendeng Engineer, to Europe to study the operation of this type of lock. Few details of these earlier locks could be incorporated into the Peterborough Lock, so the design and layout was executed by local engineers.
This was the first North American liftlock to be constructed. Its 65 foot hydraulic lift is still the highest in the world and its two cylinders are still the largest ever made. In addition, the liftlock was possibly the largest unreinforced concrete structure in the world up to that date. The concrete construction was monolithic or one pour.
During the winter of 1964-65, Dominion Bridge Company carried out a major overhaul for about 1.5 million dollars. The general appearance of the lock has been left as much as possible in its original state. The original construction cost was half a million dollars. The labour rate during construction was 10 cents per hour on a ten hour day with no coffee breaks. The equipment used was horse-drawn scrapers, one horse dump carts and a steam derrick. When one considers the amount of concrete construction knowledge at that time, it was a marvelous job, many years before its time.
Keith Patching, P .Eng.
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