1. A throttle control for controlling an internal combustion engine comprising: a. a carburetor having a throttle valve; b. a rotatable shaft connected to said throttle valve to pivot said throttle valve in a throttle opening direction towards a full open position and in a throttle closing direction towards an idle position; c. a fixed throttle lever connected to said throttle shaft and a loose throttle lever pivotable about said throttle shaft, said throttle levers having a conjoint movement condition wherein said loose lever is able to normally move conjointly with said fixed lever and a loose condition wherein said loose lever may be prevented from moving conjointly with said fixed lever, said levers having limit means engageable to limit the movement of said loose lever relative to said fixed lever in said throttle closing direction and disengageable to permit movement of one of said levers relative to the other; d. return spring means connected to said fixed lever for normally biasing said levers in said throttle closing direction to normally return said throttle valve to said idle position; e. coupling spring means for normally biasing said limit means in engagement against the bias of said return spring means to normally establish said conjoint movement condition; f. a vehicle brake system for effecting vehicle braking and including a brake pedal having a depressed condition wherein it is depressed by the operator of said throttle control and a released condition where it is not depressed; and g. mechanical linkage means including a cable and lost motion means connected between said vehicle brake pedal and said fixed throttle lever, said linkage means operative when said loose lever is prevented from moving conjointly with said fixed lever and said brake pedal in said depressed condition to pivot said throttle valve in said closing direction by overcoming the bias of said coupling spring means and disengaging said limit means to pivot said fixed lever in said valve closing direction with respect to said loose lever, said lost motion means operative with said brake pedal in said released condition to provide a slack sufficient to permit said throttle valve to be moved between said full open and idle positions by said fixed lever, said slack and said cable preventing movement of said throttle valve past said idle position by said brake.

2. A throttle control for controlling an internal combustion engine comprising: a. a carburetor having a throttle valve; b. a rotatable shaft connected to said throttle valve to pivot said throttle valve in a throttle opening direction towards a full open position and in a throttle closing direction towards an idle position; c. a fixed throttle lever connected to said throttle shaft and a loose throttle lever pivotable about said throttle shaft, said throttle levers having a conjoint movement condition in which said loose lever is able to normally move conjointly with said fixed lever and a loose condition wherein said loose lever may be restrained from moving conjointly with said fixed lever, said levers having limit means engageable to limit the movement of said loose lever relative to said fixed lever in said throttle closing direction and disengageable to permit movement of one of said levers relative to the other; d. return spring means for normally biasing one of said levers in said throttle closing direction to normally return said throttle valve to said idle position; e. coupling spring means for normally biasing said limit means in engagement to normally establish said conjoint movement condition; f. a throttle pedal linkage for normally pivoting said loose lever in said valve opening direction and including a throttle pedal having an operative condition wherein it is operated by the operator and having an inoperative condition where it is not operated by the operator, said throttle pedal operative when in said operative condition to pivot said levers in said throttle opening direction; g. a vehicle brake system for effecting vehicle braking by the operator of said throttle control and including a brake pedal having an operative condition wherein it is operated by the operator of said throttle control and an inoperative condition where it is not operated; and h. mechanical linkage means including cable means, lost motion means and linkage length adjustment means, said linkage means connected in series between said vehicle brake pedal and said fixed throttle lever and operative with said levers in said loose condition and with said throttle pedal in said inoperative condition and said brake pedal in said operative condition to pivot said throttle valve in said valve closing direction by overcoming the bias of said coupling spring means and disengaging said limit means to pivot said fixed lever in said valve closing direction with respect to said loose lever, said lost motion means operative with said throttle pedal in said operative condition and said brake pedal in said inoperative condition to permit said throttle valve to be moved between said full open and idle positions by said levers in said conjoint movement condition, and said linkage length adjustment means operative upon initial operation of said brake pedal after said linkage means have been connected to increase the length of said mechanical linkage means to prevent said throttle valve from being moved past its idle position by said brake pedal.