There are two different types of manure spreaders commonly available; the broadcast spreader and the pendulum spreader. How they operate, as well as various advantages and disadvantages, are discussed below.
The broadcast spreader, also known as a rotary spreader, has a fairly simple operation in its most basic form. You load your material into a bin called a hopper, at the bottom of which is an axle or beater bar next to an opening. Arms or paddles are attached to the axle, which work to break up the material as the axle spins, and feed material gradually into the opening in the bottom. From there, the material drops onto a rotating arm called an impeller, which spins to fling the material out at varying distances.
Broadcast spinners can be powered either by a motor or by the spreader’s own wheels. The heavier and denser your material is, the less likely you are to find a spreader powered by its own wheels. The two biggest variables as far as how wide the spread is and how heavy are the speed the spreader moves and the speed the impeller moves.
Faster impeller speeds mean wider spreading while faster ground speeds mean thinner coverage. In the case of spreaders powered by their own wheels, these two factors are connected and changing one will result in changing the other. As a result, spreaders with their own motors are more reliable and offer more consistent spreading.
It is worth noting that one of the biggest problems with broadcast spreaders is that they offer little in the way of precision. When it comes to the edges of your yard or the flower beds in your yard, there is no way of inhibiting the spread of seed or fertilizer into those areas short of erecting a temporary curtain or wall or to have somebody walk alongside your spreader holding a board up to block it.
A pendulum spreader is a type of motor powered drop spreader that has a chute which is mounted horizontal to the ground that shakes left to right. The biggest problem with a pendulum spreader is that density and particle size can have a negative effect on how evenly the material is distributed, distorting the spreader’s ability to create a uniform pattern.
A different design which fixes this problem is to use a spreader that includes a horizontal, rotating arm just above the spreader hole. This arm is designed much like those on a tiller; with projected spikes spinning at high speeds to break the material up while feeding it down into the hole.
There are other types of spreaders out there, but the broadcast and the pendulum spreaders are the most efficient when working with manure.