Peterborough Lift Lock

The Peterborough Lift Lock was built between 1896 and 1904, in an era when the strength of men, horse and steam power was shaping the transportation system of a growing nation.

The prospect of a completed Trent Valley Canal had gripped the imagination of residents for decases. But it was the concrete monolith slowly emerging from the excavation on Armour Hill that captured the attention of Peterborough visitors and residents alike.

To establish the foundations, 58,100 cubic metres (76,000 cubic yards) of sand, soil and gravel were excavated until the limestone bedrock was reached 12.2 metres (75 feet) into the rock. A foundation of granite blocks, some weighing over ten tonnes, was lowered to the bottom to provide a footing for the rams.

Then the intricate and labourious concrete work began.

In its day, the lift lock was one of the world's largest concrete structures. When completed, over 19,879 cubic metres (26,000 cubic yards) of concrete had been poured-without a single piece of reinforcing steel. The use of reinforcing steel was only just beginning, and the technique was still viewed with professional skepticism.

The installation of the steel chambres and hydraulic rams, by the by the Dominion Bridge Company of Montreal, began in 1901 and was completed in 1904. The original steelwork is in use today, mos\dified only by zinc refinishing and welding on the boat chambers. New aluminum gates were added during the mid 1960's.

How It Works

The Peterborough Hydraulic Lift Lock raises and lowers boats in two water-filled chambers a distance of 19.81 metres (65 feet).

The two massive chamber rams (1) are connected in a closed water hydraulic system. Any movement of one chamber must force an equal and opposite movement of the other chamber. The hydraulic interconnection is controlled by the crossover valve (2).

To raise boats, the upper chamber is overbalanced by taking on an extra 30 cm of water. When the valve connecting the hydraulic rams is opened, the heavier upper chamber travels downward, forcing the opposite chamber an equal distance upward.

Both chambers have giant hinged gates at both ends (3). These gates slide into retaining gates on the upper and lower canal levels by means of interlocking grooves. The chamber and canal gates pivot underwater (still locked together) allowing boats to enter or leave (4).

When the next movement of the chambvers is ready, the gates swing upright, sealing the chambres off from the canal. The vertical movement of the rams slides the gates freeof each other, and the chambers, loaded with boats, move up or down.

The extra 30 cm (1 foot) of water in the upper chamber is taked on simply by stopping below the water level of the upper canal.

The accumulator (5) provides emergency raising or adjusting power to either of the hydraulic rams. It is essentially an independant water piston created by an immense weight of iron acting on a water column.

Each ram can be adjusted or raised individually by the direct pumping of water under pressure into the rams by electrical pumps (6) but this is a very slow process. Although the chamber rams are operatedby a closed water hydraulic system, the gate-operating pistons (7) and most controls are operated by seperate oil pressure hydraulics directed by soleroid switches.

Statistical Information

Length 42.67 m (140')
Width 10.06 m (33')
Depth 2.13 m + .30m (7' + 1')
Weight with water 1542 tonnes (1,700 tons)
Volume of water 1040 cubic m (228,093 imp. gals)
Weight of extra foot of water 130.6 tonnes (144 tons)

Hydraulic Rams

Lifting Reach 19.81 m (65')
Ram Diameter 2.28 m (7 1/2')

Water Hydraulic Pressures

Ram with extra foot of water 4.00 MPa (580 psi)
Ram with other chamber and water 3.68 MPa (534 psi)
Accumulator 4.41 MPa (640 psi)


Average foundation excavation 12.19 m (40')
Hydraulic ram presswells 22.86 m (75')

Breast Wall

Height 24.38 m (80')
Thickness 12.19 m (40')
Length at base 38.40 m (126')


Height 30.48 m (100')
Constructed 1896-1904
Average time to complete transfer 10 minutes