This is an idea I have been re-visiting for at least 20 years.
Why not combine the fun of pushing a shopping cart and
hopping on..... with a human powered/ GIANT recoil- spring-
assisted "walking machine"?
Version one: A lighter constructed, frame-work using hollow
1/2 in. dia. aluminum
tubing. The basic shape would re-
semble a "classic shopping cart", only lighter. Instead of all
the extra weight of the matrix grid of the steel that is
typically used in these carts.
Different wheels : 10 in. dia. pneumatic tires on
simple wheels. A different wheel placement:
tricycle style, one in front, two in back.
The front wheel is for steering and is set up like a
standard bike. ( steering shaft,handle bar yoke,pivot shaft,
The handle bars pivot close to the front end of the
cart. The handle bars sweep back. They look like a large
'wish-bone' (if you were looking down on them).
The wide open end of the bars have a cross-bar that
them. This provides a variety of steady places to put your
hands when you are pushing the cart and steering.
There are hand brakes to stop the front and rear wheels.
At the rear of the cart there is a cross-bar or narrow
platform parallel with the rear axle. It extends out a little
beyond back of the cart. This provides more of a variety of
"hop-to" standing positions.
Now the reason this thing has to be lighter than a typical
shopping cart is .............it employs a special auxiliary
"Power-Forward" mechanism. This special device is rather
heavy in its' construction. *( see footnote)
GIANT RECOIL SPRING MECHANISM...........EXplained!!
To "power-forward" this shopping cart when you are not
running behind it and pushing and hopping,....... is to utilize
two GIANT recoil springs mounted on either side of it.
Clock-work springs that are 3 feet in dia. could be mounted
and geared into a simple transimission. Using a series of
gears and a single hand-activated lever to operate.
Forward movement of the cart created by pushing it would
provide enough energy to wind up the springs. Using
reduction gearing, very little effort would be needed.
Springs that are 3 ft. in dia. have about 25 ft of linear
spring-metal in them that will need to be wound.
Once the springs have reached maximum wound capacity
they would self-latch with a simple ratchet lock key.
Basic forward-only clutching would allow the cart,
unimpeded forward movement.
The GIANT clock springs would be engaged as an auxiliary
form of energy- forward, if you were to become fatigued
from running,walking,pushing and hopping. And it could
assist with movement up inclined roadways.
*(footnote) Clock-work springs are manufactured in many
diameters. Common ones are used in most wind up clocks,
timer devices, and simple toys. A ribbon of spring steel
is wound around a hub. A key or hand crank combined with
some gearing and a ratchet-key lock, wind and contain
the springs' energy potential. Disengaging the ratchet-key
lock allows the spring-coil to unwind generating a
energy force which can be regulated by a simple governor.
Spring steel is fairly heavy and the "can" which houses it
is often made of steel which also heavy.