This invention relates generally to toy vehicles powered by wind-up spring motors, and more particularly to a toy vehicle of this type having a high-torque, four-wheel drive, the wheels being driven at a governed speed whereby the vehicle is capable of riding over small hills and other obstacles.
The use of wind-up spring motors for propelling miniature vehicles is commonplace in the toy field. Traditionally, these motors are wound by means of a key which engages the spring shaft. But because small children have difficulty operating a key, the trend in recent years has been toward so-called pull-back toys in which a coupling is provided between the rear wheels and the spring motor. In this arrangement, when the toy is grasped by the player and pulled back along the ground, this reverse movement acts to wind the spring. And when the vehicle is then released, the unwinding spring acts to propel the vehicle in the forward direction.
Among the patents disclosing pull-back vehicles are those to Higashi, No. 3,798,831 (Tonka Corp.) and to Darda, 3,812,933. Tonka and Darda miniature cars are well known in the toy field.
One difficulty experienced with pull-back toy vehicles in which the rear wheels act to wind up the spring motor, is that if the player holding the car against the ground applies most of his pressure against the front wheels, the rear wheels will not frictionally engage the ground and the spring will not then be wound, Also, with a pull-back toy, when the spring motor is fully charged and the vehicle is released, the vehicle immediately leaps forward and rushes at relatively high speed in the direction chosen by the player. As a consequence, the motor, whose release of energy is uncontrolled, quickly winds down; and though the motor is exhausted, the car continues to move a fairly short distance by reason of its inertia.
A pull-back vehicle of the conventional type is an effective toy when one plays on a level, unobstructed surface. But these spring-wound vehicles rapidly dissipate their power and are therefore incapable of climbing up miniature hills, inclined surfaces or other obstacles placed in their path. Thus while it is fun for a player to see his car race over a level surface, he may be disappointed when the car fails to travel up an inclined path or overcome other obstacles.
In the real world of cars having internal-combustion engines, when the need arises for a car to negotiate rough terrain or steep hills, use is made of a vehicle having traction wheels and a four wheel drive, the car operating in a gear ratio affording high torque. But an equivalent arrangement has not heretofore been found in spring-powered toy vehicles, for their existing structures do not lend themselves to such an arrangement.
Since what affords the greatest play satisfaction to children are miniature vehicles that are capable of performing in the manner of a real vehicle, the inability of toy vehicles to climb hills and to ride over other obstacles has created a need for toy vehicles having this impressive capability.