Compiled by J Fuls (Pr Eng)

It is always beneficial for a farmer to fully understand how all the tools and devices used on the farm work. First, better understanding means better operation and second, in the event of a breakdown the farmer often has to improvise to fix his equipment, especially when no spare parts are available.

This month we shall take the knapsack sprayer apart to look in detail at the inner workings. We thank the ARC Institute for Agricultural Engineering in South Africa, who made this article available to the readers of ProAgri Zambia.

Knapsack sprayers do not all look the same inside, but we shall look at the one already discussed:

The manual will have more detail than this article. Always keep the manual ready when working on your sprayer. Always work on a clean surface like a newspaper or a clean table or floor. The parts must be kept clean. Some parts are small and may easily be misplaced, so keep them together in a container. Arrange the parts in the order they are removed from the sprayer, to prevent confusion on re-assembly.

Proceed as follows:

1. Pull out the pin that keeps the rod in place onto the pump and remove the rod.

2. Unscrew the hose connector and pull out the plastic tube from the pump.

3.Unscrew the lid and remove the filling screen.

4. Put your hand into the spray tank and remove the stirring spoon from the pump

5. Unscrew the pump nut and pull out the pump cylinder

6. Put one hand inside the tank to hold the push rod. Use a special spanner and unscrew the nut at the bottom to remove the push rod.

After cleaning the parts properly with soap and water, and replacing damaged parts, the knapsack sprayer can be assembled again.

Putting the knapsack sprayer together

Assembling the sprayer is the opposite of taking it apart. Also consult the manual to make sure it is done correctly.

Faults and repairs

Next month we shall look at how to use the knapsack sprayer in the correct manner. Published with acknowledgement to the ARC Institute for Agricultural Engineering for the use of their manuals. Visit www.arc.agric.za for more information.