Fig. 62 illustrates a centrifugal type of governor which has been used by a number of prominent commercial car builders. The governor is placed at the front end of the motor and is driven through spiral gears from the magneto drive shaft. As the motor speed increases the weighted levers open and raise a sleeve which operates the auxiliary throttle valve in the intake manifolds, by means of a forked lever bearing in the sleeve and a flexible shaft which operates a rack meshing with a small gear on the auxiliary valve shaft. As the speed decreases the pressure of the governor spring returns the operating parts to their neutral position.
Fig. 62. Centrifugal Type of Governor.
Fig. 63 shows a hydraulic type of governor used by some commercial car builders. It is mounted between the intake manifold and the carburetor. The operating mechanism is combined in a unit with the governor proper, making it a simple and compact unit. The water chamber is connected with the water pump and as the latter's speed increases, the water pressure raises and forces the diaphragm down. This diaphragm has a stem which bears on the throttle lever and is controlled by a coiled wire spring. The lever in turn forms a segment with several teeth and meshes with a small gear on the throttle valve shaft. As the pressure decreases the spring returns the diaphragm to its original setting and opens the throttle valve. The water chamber cover, operating lever housing and the spring retaining plug are sealed so that the governor cannot be tampered with, without first breaking either one of the three seals.
In both of the above types the maximum speed may be changed by increasing or decreasing the spring tension.
Fig. 63. Hydraulic Type of Governor.
An automatic type of governor is shown in Fig. 64, in which the speed is regulated by governing the velocity of the inflowing gases. This device consists of a throttle connected to a disc that is allowed to float under a constant spring tension, in a tapered conduit, the tension of the spring determining the maximum engine speed. The slightest change in the velocity of the incoming gases caused by a difference in engine speed will affect the position of the disc in the conduit and also change the position of the throttle immediately, giving the engine more or less gas as the conditions may require. An auxiliary control lever is provided, giving the operator access to any engine speed under the maximum controlled by the governor. This governor is designed to be mounted between the intake manifold and the carburetor and does not require any form of drive whatever, its operating mechanism being self-controlled.
The Krebs truck is equipped with a centrifugal type of governor which controls the motor and car speed. The spark and throttle are so connected to the governor that it constantly sets them for the power, load and speed that may be required, without regard to road conditions. The governor is also so contrived that when the clutch is disengaged, the motor continues to run at the same speed, preventing the driver from racing the engine. Engaging the clutch causes the throttle to open wide until the car reaches the speed at which the governor is set. The manufacturer of this governor claims that it takes the entire responsibility of handling the motor at all speeds and all loads. This governor is shown in Fig. 65.
Fig. 66 illustrates the Pierce engine governor, which also operates on the centrifugal principle. It differs from the above in that it is designed to he mounted between the intake manifold and the carburetor, making it more adaptable to motors in general. The drive may either be taken from the earn shaft of the motor or countershaft of the transmission. As the motor speed reaches the maximum setting of the governor, the triangular weights open and move endwise on the shaft upon which they are mounted, which in turn moves the operating rod. The end of this rod carries a rack gear which is in mesh with a small gear on the butterfly valve shaft. As the weights close a spring returns the rod to its neutral position. The governor also has a speed adjustment, so that any desired motor speed may be obtained. This adjustment is sealed so that it cannot be tampered with.
Fig. 67 shows the Pierce speed controller which operates on the same principles as the Pierce governor. The drive is taken from the front wheel and is similar to a speedometer drive. It is so constructed that it is impossible to remove the driving gear without breaking the seals and removing the front wheel. The triangular weights are placed at right angles to the valve operating rod, the governor shaft movement being transmitted through a bell crank. The controller is provided with a variable speed dial, which changes the spring pressure on the operating rod and pemits instant adjustment of speed to suit individual requirements, automatically controlling vehicle speed, leaving the motor free at all times. This controller may also be provided with a lock so that it is impossible for any one to start the vehicle without the key.
The housing of both devices are made of aluminum, so that a minimum weight is carried by the intake manifold. The chief advantage claimed for these devices, is their adaptability to any vehicle, as it is only necessary to drop the carburetor one inch to one and one-half inches. In case of repairs it is a very simple matter to remove the governor or controller entirely, raise the carburetor and the vehicle need not be laid up pending the return of either device.
Fig. 64. Automatic-Type Governor.
Fig. 65. Another Type of Centrifugal Governor.
Fig. 66. Pierce Centrifugal Type Governor and Drive.
Fig. 67. Pierce Centrifugal Governor.