Diesel vehicle speed control system

In a vehicle having a diesel engine having multiple cylinders and fuel supply means including multiple metering valves and injectors, one set for each of said cylinders, fuel control means mechanically coupled to all said metering valves to control the volume of fuel delivered therefrom to said injectors, the improvement which comprises:

• a fluid pressure responsive actuator having a variably positionable actuator arm engageable with said fuel control means to effect movement thereof in a fuel limiting direction, said arm being movable in said fuel limiting direction in response to fluid pressure applied to said actuator, said actuator including bias means for biasing said arm for travel in an opposite, non-fuel limiting direction upon removal of fluid pressure from said actuator;
• pneumatic pressure fluid supply means including a source of air under superatmospheric pressure;
• conduit means connecting said fluid supply means and said actuator, and including solenoid valve means having an open position for applying said air to said actuator, and a closed position for venting air from said actuator to atmosphere;
• a speed sensing element responsive to one of vehicle or engine speed to generate a sensed signal responsive to sensed speed;
• system control means to receive said sensed signal, compare said signal to a preset signal level corresponding to a maximum permissible speed, and generate an electrical control signal when said sensed signal deviates from said preset signal level;
• means interconnecting said system control means to said valve means to actuate said valve means between said open and closed positions, according to the character of said electrical control signal;
• and
• air pressure restrictor means interposed between said pressure fluid supply means and said actuator, in the path of air applied to said actuator, to impede air flow to said actuator to slow extension of said arm in said fuel limiting direction, whereby said fuel is gradually restricted, permitting the speed of said vehicle to react to said reduced fuel flow during travel of said arm in said fuel limiting direction, and said restrictor means being out of the path of air venting to atmosphere from said actuator, whereby said arm is enabled to move relatively rapidly under the bias of said bias means in said non-fuel limiting direction, said restrictor means comprising a porous plug of limited permeability.