F', F_{2}, F_{3}, F_{4}, etc., represent additional secondary pinions
grouped around the center pinion, mounted on studs in the shell, and
made of different diameters, so that they are driven by the center
pinion at different speeds. Each of the secondary pinions is formed
with a neck or journal, _f_, projected out through the side of the
shell, so that the external pinion, H, may be applied to any one of
the necks at will in order to communicate motion thence to the gear,
I, which occupies a fixed position, and from which the fertilizer or
other mechanism is driven.

In order to drive the gear, I, at one speed or another, as may be
demanded, it is only necessary to apply the pinion, H, to the neck of
that secondary pinion which is turning at the appropriate speed and
then turn the shell bodily around the axle until the external pinion
is carried into engagement with gear I, when the shell is again locked
fast. The axle communicates motion through D, E, and P to the center
pinion, which in turn drives all the secondary pinions except F. If
the external pinion is applied to F, it will receive motion directly
therefrom; but if applied to either of the secondary pinions, it will
receive motion through or by way of the center pinion. It will be seen
that all the pinions are sustained and protected within the shell.

The essence of the invention lies in the introduction of the pinions D
and E between the axle and the series of secondary pinions to reduce
the speed.

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