About the Project

• Background to the Project
• Initial Workshops
• Launching the Project
• Leeds & Liverpool History
• The Workings of a Lock

Johnson's Hillock

• Introduction to the Walk
• Walk Guide - Section 01
• Walk Guide - Section 02
• Walk Guide - Section 03
• Walk Guide - Section 04
• Walk Guide - Section 05
• Walk Guide - Section 06
• Walk Guide - Section 07

Salterforth to
Greenberfield

• Introduction to the Walk
• Walk Guide - Section 01
• Walk Guide - Section 02
• Walk Guide - Section 03
• Walk Guide - Section 04
• Walk Guide - Section 05
• Walk Guide - Section 06
• Walk Guide - Section 07

About the Project - The Workings of a Lock

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Canals consist of a series of man-made water channels at different levels. These are connected by locks which allow boats to move up or down between the levels. At a flight of locks, where several locks are close together as at Johnsons Hillock, there only needs to be a short water channel between each lock. The channel needs to be long and wide enough to allow boats travelling in opposite directions to pass each other. A lock consists of a chamber with gates at either end to hold back the water. The size of the lock chamber dictates the largest boat which can use the canal. Water is controlled by sluices, called paddles on a canal, which are opened or closed by fitting a handle, known as a windlass, onto a square-ended shaft connected to gears. Turning the windlass turns the gears and these raise or lower the paddle. Paddles are found on the gates and at the side of the upper entrance to the lock, the latter being called ground paddles.

The water comes from reservoirs near the canal's summit level at Foulridge. Enough water is allowed out of these reservoirs to provide water for the locks and for any leakage or evaporation. The water from the reservoirs passes down the canal as boats use the locks. Any excess is carried around locks by a ‘byewash', a small sloping channel on the opposite side of the lock to the towpath.

Operating a lock is quite simple. The most important thing to remember is not to have the paddles at either end of the lock open at the same time as this allows water to run to waste through the lock. Wasting water is a sin on the canal. A boatman approaching a lock from above would first check that all the paddles were closed. He would then open those in the upper gates, allowing the lock chamber to fill. With the water in the lock at the same level as the upper canal, he can open the upper gates for the boat to enter the lock, carefully closing both the paddles and the gates after the boat is in the lock.

After securing the boat to bollards on the lock side, the boatman would open the paddles in the lower gates to let the water out of the lock. As the water level fell, he would slacken off the ropes holding the boat to allow it to descend with the water. It was important to keep the boat away from the upper gates. They rested on a step in the stonework of the chamber, called a sill. If a boat caught on the sill it could be badly damaged and sink. When the water in the lock had fallen to the same level as the lower canal, the boatman could open the lower gates. After untying the boat so it could leave the lock, he would close the gates and the paddles to make the lock ready for the next boat.

The bollards for stopping the boat from moving around in the lock were usually of cast iron. Some of the old bollards on the locks here have been well used, and you can feel the grooves caused by the ropes wearing into the iron. Ropes would pick up grit from off the towpath and this made them work like sand paper when rubbing against the iron or stonework of locks and bridges. A three-dimensional panel at the second lock shows the three phases of a boat passing through a lock, ie entering the lock, descending the lock and leaving the lock. Note the position of the lock gates for each phase.