Modifications to a pottery wheel
Practical Action
Modifications Effected:
Criteria (a) and (b), required some form of energy storage and as was done from early times, an
inertia wheel was resorted to.
Thus the only modification to be effected was modifying the drive mechanism, which should also
suit rural female operators. Electric motor drives had to be abandoned due to the rural nature of
the use of the wheel.
Using concepts of ergonomics for most effective use
of human effort, the drive mechanism was finally
developed to consist of:-
A bicycle freewheel fitted on the shaft
connecting the worktable to the inertia
wheel.
A housing to contain the freewheel.
A thin wire cable wrapped round the housing
and taken over two pulleys attached to the
frame-
Two stirrups attached to the end of the wire
cable to serve as pedals and footrests.
In operating the drive the operator would push one
leg down, engaging the ratchet of the freewheel and
thus November 1977 turning the spindle and the
wheels (inertia and worktable). At the end of this
stroke, the other leg would have come up to the
topmost point of its travel and on pushing this foot
down the other leg is brought up. Due to the
freewheel's one way engagement, this travel does not
impart a reverse
rotation. Travel
of one limb
would thus
engage the drive
to the inertia
wheel while the
travel of the
other leg would
bring the earlier
5
leg to its original
position. Up and
7
down motions of
the limbs would
8
thus impart
rotary motion to
the inertia
wheel.
Figure 4: St. Ives Kickwheel
1
2
6
4
3
As the drive has beenFimgouvreed5a:wTahyefrMomodifiedFiWguhreee5l: The Modified Wheel
the inertia wheel and made
reciprocatory foot motion, restrictions on the inertia
1 Frame
2 Worktable
wheel dimensions were removed. This enabled a
better inertia wheel with a larger ratio of inertia to
weight to be incorporated. A composite inertia wheel
3 Inertia Wheel
4 Spindle
5 Seat (adjustable horizontally and vertically)
6 Drive Mechanism (freewheel and housing)
consisting of a circular mild steel plate of 1/4" inch
thickness
7 Cable (length adjustable at hook)
8 Pulleys (position along seat frame adjustable)
3