Pullback motor
Encyclopedia
A pullback motor is a simple clockwork motor used in toy cars.
Pulling the car backwards (hence the name) winds up an internal coil spring
. When released, the car is propelled forwards by the spring. Once the spring has unwound and the car is moving, the motor is disengaged by a clutch
or ratchet
and the car then rolls freely onwards.
Most of these cars are otherwise free-rolling. Winding them up requires them to be pushed downwards, engaging the clutch. As the motor is only engaged for winding whilst held down, the complete winding must be completed in one pass, unlike the flywheel motor. A few motors have an internal one-way clutch that allows winding with a back-and-forth motion.
Some pullback motors, usually intended for racing in pairs, have used a catch and release mechanism to retain their springs. These may be wound separately, then launched together by releasing their spring triggers. Darda
use such a mechanism for their Stop'n'Go motor. This is pre-wound, then releases automatically when shunted from behind. This allows relay race
s to be set up with multiple cars.
A few pullback motors are used in toys other than cars. The K'Nex
construction toy has such a motor, as have some later Meccano
sets.
The very simplest of these motors may use a stretched rubber band
as a linear spring, rather than a coil spring. These are bulky and less powerful but require little manufacturing sophistication: coil springs, although apparently simple, demand a highly developed steel metallurgy
. For this reason these toys are usually home- or crafts-made.
Pulling the car backwards (hence the name) winds up an internal coil spring
Coil spring
A Coil spring, also known as a helical spring, is a mechanical device, which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces...
. When released, the car is propelled forwards by the spring. Once the spring has unwound and the car is moving, the motor is disengaged by a clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
or ratchet
Ratchet
Ratchet may refer to:* Ratchet , a mechanical device that allows movement in only one direction* Ratchet, a tool also known as a socket wrench* Ratchet , a music instrumentIn film and television:...
and the car then rolls freely onwards.
Most of these cars are otherwise free-rolling. Winding them up requires them to be pushed downwards, engaging the clutch. As the motor is only engaged for winding whilst held down, the complete winding must be completed in one pass, unlike the flywheel motor. A few motors have an internal one-way clutch that allows winding with a back-and-forth motion.
Some pullback motors, usually intended for racing in pairs, have used a catch and release mechanism to retain their springs. These may be wound separately, then launched together by releasing their spring triggers. Darda
Darda (toy)
Darda is the name of a German toy car racing set which was most popular in Europe and the USA throughout the '80s and '90s. Today the toys can be ordered online from retailers such as ,...
use such a mechanism for their Stop'n'Go motor. This is pre-wound, then releases automatically when shunted from behind. This allows relay race
Relay race
During a relay race, members of a team take turns running, orienteering, swimming, cross-country skiing, biathlon, or ice skating parts of a circuit or performing a certain action. Relay races take the form of professional races and amateur games...
s to be set up with multiple cars.
A few pullback motors are used in toys other than cars. The K'Nex
K'NEX
K'Nex is a brand name of a construction toy system invented by Joel Glickman, designed and produced by Industries of Hatfield, Pennsylvania, USA. Currently Michael Araten is the president of the organization. The name is, presumably, a phonetic variation of connects, and is pronounced the same way...
construction toy has such a motor, as have some later Meccano
Meccano
Meccano is a model construction system comprising re-usable metal strips, plates, angle girders, wheels, axles and gears, with nuts and bolts to connect the pieces. It enables the building of working models and mechanical devices....
sets.
The very simplest of these motors may use a stretched rubber band
Rubber band
A rubber band is a short length of rubber and latex formed in the shape of a loop and is commonly used to hold multiple objects together...
as a linear spring, rather than a coil spring. These are bulky and less powerful but require little manufacturing sophistication: coil springs, although apparently simple, demand a highly developed steel metallurgy
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...
. For this reason these toys are usually home- or crafts-made.