Abstract: An internal combustion engine includes a plurality of cylinders, a plurality of fuel injectors, compression brake units operatively associated the cylinders, an engine speed sensor and an engine control unit (ECU) for controlling the fuel injectors and the compression brake unit as a function of at least sensed engine speed.

Abstract: A method is provided for accommodating the purge vapors from an evaporative emission control system of an automotive vehicle. The method includes a means of learning the bank-to-bank distribution of purge vapors within the engine manifold. As such, the fuel to air ratio delivered from various injectors can be selectively controlled to accommodate the purge vapor at that bank of the engine and maintain the desired fuel to air ratio.

Abstract: In a control arrangement for an internal combustion engine having a cylinderhead with a compressed air discharge valve and a compressed air system with a compressed air tank to which compressed air can be supplied from the engine cylinder by way of a connecting line, pressurized control fluid can be supplied to the compressed air discharge valve for opening the compressed air discharge valve for motor braking operation of the engine, and a bypass line including a control valve is provided by way of which the compressed air discharge valve can be directly controlled for supplying compressed air to the compressed air tank.

Abstract: A drive unit includes a hydrodynamic retarder having a rotor paddle wheel, a stator paddle wheel, and a housing surrounding the rotor and stator wheels. The unit includes a coolant cycle system for an internal combustion engine, the coolant for this coolant cycle also being a working medium of the retarder. The drive unit further includes a working medium container for the coolant. A first pipe connects a hydrodynamic center of the retarder to a valve. A second, leakage pipe is disposed between a working medium outlet of the retarder and the valve. A third pipe is disposed between the valve and the working medium container. The valve is designed such that in a first position, a conducting connection is established between the working medium container and the leakage pipe to provide for a pumping operation of the retarder. When the valve is in a second position, a conducting connection is established between the working medium container and the first pipe for a braking operation of the retarder.

Abstract: A drive unit includes a hydrodynamic retarder having a rotor paddle wheel, a stator paddle wheel, and a housing surrounding the rotor and stator wheels. The unit has a coolant cycle system, through which a coolant flows, the coolant also being a working medium of the retarder. The drive unit further includes a working medium container for the coolant and a pipe having a valve. The pipe is disposed between the retarder and the working medium container. The unit also has a coolant feed line to the retarder.

Abstract: A method for controlling an engine for a model and a device therefor capable of improving throttle response. Feed of fuel to the engine is increased during acceleration of the engine and decreased during deceleration thereof. This permits a rotational speed of the engine to be smoothly and rapidly varied, to thereby reduce vibration of the engine and prevent knocking and breathing of the engine. Also, adjustment of a trim provided on a side of a controller leads to adjustment of a needle valve, so that the adjustment may be facilitated.

Abstract: An improved engine retarder cycle in which the exhaust valve(s) or a dedicated retarder valve is opened during the compression stroke much earlier than in prior art retarder cycles. By opening the retarder valve earlier, the cylinder pressure is not allowed to build to as high a level as in the prior art, thereby requiring less force to push open the retarder valve. Additionally, increased retarder power is generated by increasing the charge of air that is in the cylinder during the compression stroke. This is accomplished by increasing the turbocharger boost by eliminating wasted flow in and out of the exhaust valves. The increased air mass is also created by incorporating a retarder intake event which opens the valve(s) starting at approximately mid-intake stroke and ending in the first half of the compression stroke. The result is increased retarding work and decreased mechanical loading on the engine.

Abstract: A braking control for an engine permits the timing and duration of exhaust valve opening to be accurately determined independent of engine events so that braking power can be precisely controlled.

Abstract: An electronic control for controlling a high idle set value of equipment having an engine is disclosed. The control includes an electronic controller electrically connected to a rocker switch comprising a high idle switch and a low idle switch. An engine speed sensor and a decelerator pedal position sensor are electrically connected to the electronic controller. The electronic control permits the equipment operator to program a desired high idle set point value. The control thereafter produces an engine speed command based on the high idle set point value. A decelerator pedal is provided to permit the equipment operator to reduce the engine speed command value below the high idle set point value.

Abstract: The slave piston drive train in a compression release engine braking system includes a slave piston with a rigidly connected extension. The end of the extension remote from the main body of the slave piston is spherically convex. A bearing pad or foot fits in swivel fashion on this spherically convex end. The outer surface of the foot opposite the spherically convex extension end is substantially flat and bears on a substantially flat surface on an exhaust valve rocker arm.

Abstract: A compression braking system for an internal combustion engine having at least one working piston including a master piston operated by an engine component such as a fuel injector actuating mechanism and a slave piston fluidically connected with the master piston to open an engine exhaust valve wherein a pressure relief valve is provided to prevent excessively high pressure supply fluid from a low pressure supply circuit from reaching the high pressure circuit connecting the master and slave pistons thereby preventing inadvertent and excessive movement of the slave piston and possible damage to the engine. The pressure relief valve is fluidically connected to the low pressure supply circuit upstream of a control valve which separates the low and high fluid circuits and opens to vent fluid from the low pressure circuit while allowing continuous, uninterrupted operation of the engine in the braking mode.

Abstract: The slave piston drive train in a compression release engine braking system includes a slave piston with a rigidly connected extension. The end of the extension remote from the main body of the slave piston is spherically convex. A bearing pad or foot fits in swivel fashion on this spherically convex end. The outer surface of the foot opposite the spherically convex extension end is substantially flat and bears on a substantially flat surface on an exhaust valve rocker arm.

Abstract: Air compression systems for internal combustion engines are utilizing an integral part of the engine to produce the compressed air necessary for operating the brakes of a vehicle. The ability to produce compressed air from an integral part of the engine is important in order to reduce the cost and weight associated with the engine and to increase performance capability and reliability. The integral air compression system includes a valve means associated with one of a plurality of combustion chambers. A housing is connected to a cylinder head and has first and second bore. A master piston is disposed within the first bore to define a first oil chamber. A slave piston is disposed within the second bore to define a second oil chamber. A means fluidly connects the first and second oil chambers. The master piston is forced toward the first oil chamber when another one of the combustion chambers is in the exhaust stroke.

Abstract: The present invention relates to an internal combustion engine with compressor function comprising, in addition to intake and exhaust valves for each cylinder, an extra exhaust valve in at least one cylinder, which extra exhaust valve, in its open position, puts the cylinder chamber in communication with valve means containing an exhaust duct and disposed to permit exhausting of intake air to a pneumatic system but prevent intake of air to the cylinder chamber via said exhaust duct.

Abstract: A vehicle engine speed controller for automatically determining the electrical load demand made of the engine electrical system from portable auxiliary and vehicle mounted electrically operated or controlled equipment, singly or in combination, and controlling the engine throttle speed setting through a governor with certain fail safe control mechanisms.

Abstract: An engine brake for a multicylinder internal combustion engine includes valves that can be periodically opened briefly, in each case outside the exhaust stroke. In the vicinity of the applicable valve drive, a hydraulic piston is provided that is triggered synchronously with the engine rpm via an associated control line by a hydraulic pressure distributor fed by a pump. To improve the accuracy of control over the entire engine rpm range, the various valves are assigned a central positive displacement pump that runs synchronously with the camshaft rpm and whose outlet line leads to the hydraulic pressure distributor, which has a distributor disk. In engine braking operation, an alternating connection of the applicable control line to either the pump outlet line or a low-pressure region of the hydraulic control circuit is effected synchronously with the engine rpm by means of the distributor disk.

Abstract: A valve control apparatus particularly suited for a diesel engine brake. There is an hydraulic actuator having a piston which contacts the valve stem of an exhaust valve. The actuator is independent of the exhaust valve opening mechanism. There is a device, such as an electromagnetically activated valve, which can releasably shut off a flow of fluid from the hydraulic actuator after the exhaust valve is opened by the exhaust valve opening mechanism. The exhaust valve is prevented from closing until a flow of fluid from the hydraulic cylinder is permitted just before top dead center of the compression stroke.

Abstract: The invention is directed to a method for adjusting the idle air actuator in the intake system of an internal combustion engine during idle or overrun operation, the method comprising the steps of: transferring the idle air actuator into a non-driven position in a load area outside the idle or overrun operation; continuously monitoring outside of idle and overrun operation as to whether such a change of operating variables takes place which makes a transfer into idle or overrun operation probable; and, if so, driving the idle air actuator with a value which is determined so that the idle air actuator assumes that position, which, when reaching idle or overrun operation, will presumably by substantially the correct position.

Abstract: A method for controlling an internal combustion engine is proposed, in particular in conjunction with control systems for engine power, in which, in order to avoid potentiometer failures due to deposits of insulating abraded material on the potentiometer track due to the movement of a positioning component, in particular a throttle flap, in overrun operation, with released accelerator pedal and above a pregiven resume engine speed where there is fuel cutoff, the positioning component is briefly moved out of its fixed position or is closed beyond its pregiven idle position. On reaching a certain position for upon renewed fuel supply due to the engine speed falling below the resume engine speed, the positioning component is abruptly reset to its fixed position.

Abstract: The brake system comprises a shaft interposed between two propeller shaft segments via universal joints, a radial compressor selectively connected with the shaft, a casing for housing the radial compressor and the shaft with the universal joints being outside the casing, and stay members mounted on the casing for allowing the casing to be suspended from the vehicle body. The brake system has a radial compressor which is selectively connected with the propeller shaft and consumes energy of the engine. The energy consumed is a result of the compressor serving as a brake force. The casing is fixed to the vehicle body so that the brake system also serves as a center bearing of the propeller shaft.

Abstract: A process and a device for air proportioning during idling or overrun mode of operation in an internal-combustion engine are provided. During idling, the internal-combustion engine is regulated to a nominal speed by means of a PI controller (203, 204) and a preliminary air rate control value is determined as a function of temperature, gear position and air-conditioning state of the vehicle. At the same time, the actual air mass or air intake rate (60) is measured and the difference value of the actual air intake rate and the preliminary air-rate control value is stored in a store (304). During overrun, the air-mass throughput of the internal-combustion engine is regulated to this stored value. Furthermore, the control receives a series of auxiliary variables which make it easier to carry out the control as a function of the particular operating mode.

Abstract: In an internal combustion engine having a fuel/air delivery system such as a carburetor (12) supplying a fuel/air mixture for combustion by the engine, a deceleration enrichener system includes a valve (10) operated by engine manifold vacuum (14) and enrichening the fuel/air ratio of the mixture upon deceleration of the engine by decreasing the amount of air in the mixture. The valve (10) closes the idle air inlet port (16) of the carburetor (12) upon deceleration.

Abstract: The invention relates to an internal-combustion engine-braking device and comprises a throttle valve actuated by a control piston both of which are arranged in a controlled bore in a cylinder head. To ensure lubrication of the control piston in a simple way, the control bore is equipped with a connecting orifice to the oil return bore leading from the engine rocker-arm space into the crankcase.

Abstract: An engine brake system comprising, in combination, a power absorbing oil pump driven in operative linkage with the crank shaft of the engine and a mechanism for controlling discharge pressure of said oil pump is disclosed. The pressure control mechanism comprises a main valve designed to be opened with a lift inversely proportional to the braking torque of the engine, a mechanism for adjusting the pressure on the back side of the main valve and a valve for switching the pressure on the back side of the main valve, all of which are provided in a valve box having an oil hole communicated with the discharge port of the oil pump. According to this system, in accordance as the engine speed increases, the lift of the main valve is reduced to elevate the power absorbed by the oil pump. Thus, this system is particularly useful for engine brake for vehicles.

Abstract: An engine brake device including a bypass line connecting an inlet line and an exhaust line of an engine so as to guide air from the inlet line to the exhaust line, a compressor rotatably disposed in said bypass line with its output shaft being connected to a crankshaft of the engine and opening-closing device for opening said bypass line upon engine braking.

Abstract: The invention includes an apparatus for retarding an engine. There is a mechanism, such as a master and slave cylinder arrangement, for cracking open each exhaust valve of each cylinder of the engine near top dead center of each compression stroke. There is also provision for increasing the pressure of gases in the exhaust manifold sufficiently to open exhaust valves of other cylinders on the intake stroke after each exhaust valve on the compression stroke is so opened. The provision for increasing the pressure of gases in the exhaust manifold may include retarding timing of the cracking open of the exhaust valves on the compression stroke and a valve or other device for restricting a flow of exhaust gases from the exhaust manifold.

Abstract: A fuel supply control system for use in an engine includes a feeder for supplying fuel to the engine in an amount suitable for operating conditions of the engine, a detector for detecting a decelerating state of the engine, and a correcting device for, upon detecting the deceleration, increasing a rate of fuel supply so that combustion may be stabilized to prevent car-bucking. The system further includes a brake detector for detecting an operative state of a brake device of the vehicle, and a limiter for, upon operation of the brake device, limiting the increase of fuel supply whereby the fuel consumption efficiency can be improved. During operation of the break device, car-bucking is restricted by a braking force so that substantially no vibration is transmitted to a driver.

Abstract: An energy conserving system for use with vehicles with an internal combustion engine and friction brakes includes a first valve in the air/fuel feed to the engine, a second valve in the exhaust line, a tank for pressurized air, and conduits between the tank and the valves. Actuation of a control system enables a first sensor to determine whether the brakes are being applied which opens the second valve to divert exhaust to the tank. During startup, the compressed air with or without fuel is used to reciprocate the pistons for a limited period after which fuel/air mixture feed at atmospheric pressure is commenced for normal engine operation. During engine startup, the brake sensor is not activated; and fuel supply to the engine is only cut while braking. However, fuel can be mixed with pressurized air from the pressure tank at any time depending upon accelerator position to make the engine work as a compressed air supplied engine or as a turbo combustion engine.

Abstract: An intake system for an internal combustion engine having an air/fuel ration control device for closing the vent on a float chamber. The increased pressure within the float chamber from the incoming fuel enrichens the air/fuel mixture to the engine. The vent closure is effected by a valve controller responsive to intake vacuum. The controller is activated by vacuum experienced during engine braking. A bistarter choke system is disclosed including means for disabling the air/fuel ratio control device using either a switching apparatus or the higher pressures within the choke mechanism.

Abstract: The swash plate engine is provided with an Aspin type rotary valve system with a variable compression capability. The engine may be of four-piston type or six-piston type. The size of the combustion chambers can be changed from time to time to vary the compression ratio. The engine may also be coupled with an accumulator to store the energy of braking for subsequent acceleration of the engine.

Abstract: The internal combustion engine includes a carburetor having an air induction passage communicating with the engine combustion chamber and a throttle valve mounted inside the induction passage for pivotal movement between an idling speed position and a range of high speed positions, a primary fuel delivery system including a fuel pump for supplying fuel to the carburetor during normal engine operation, and a secondary fuel delivery system for supplying a flow of enrichment fuel to the engine combustion chamber, independently of the primary fuel delivery system, during periods of rapid engine deceleration.

Abstract: An engine governor having overriding means for limiting the flow of fuel to an engine, means for moving the overriding means to an intermediate reference position upon actuation of the governor, and means for moving the overriding means from the reference position to other positions for limiting the flow of fuel to that suitable for operating the engine at speeds close to a set speed. Means for actuating the governor before the engine reaches the set speed, means for moving the overriding means from the reference position to the other limiting positions at a very slow rate, and means for moving the overriding means toward limiting the fuel flow to a minimum when an over-running load causes the engine speed to run a predetermined amount above the set speed.

Abstract: A method for controlling the quantity of supplementary air being supplied to an internal combustion engine during idling operation thereof in a feedback manner responsive to the difference between the actual engine rpm and desired idling rpm. When the engine is operating in a decelerating condition with the throttle valve fully closed, a provisional value of desired idling rpm is set, which is larger than a proper value of desired idling rpm by a predetermined amount. The quantity of supplementary air is controlled in a feedback manner responsive to the difference between the actual value of engine rpm and the provisional value of desired idling rpm for a predetermined period of time from the time a predetermined condition of feedback control for bringing the engine rpm to the provisional value of desired idling rpm has been satisfied as a result of comparison between the actual value of engine rpm and the provisional value of desired idling rpm.

Abstract: A throttle valve control apparatus having a valve closing device for closing the throttle valve beyond the idling position thereof. The valve closing device is controlled by a control mechanism which is responsive to engine speed and includes an engine speed sensor. The closing device is operated at the time of deceleration of the engine from the condition that the engine speed is above a predetermined minimum ON speed and is released from operation when the engine speed is lowered to a predetermined OFF speed which is near the idling speed. The ON speed is set to be above an upper-limit of an adjustment error range predetermined about the actual idling speed.

Abstract: The actual rotational speed of an internal combustion engine is detected, and the detected rotational speed is compared with upper and lower limit speed values to generate a control signal indicative of the change in the idle air flow to the engine to maintain the actual rotational speed within a desired range. The idle air flow to the engine is adjusted in response to the generated control signal. The above detection of the actual rotational speed or the adjusting is started after a predetermined period of time is passed from the moment when the engine falls into a predetermined idling condition.

Abstract: A feedback control system for controlling the rotational speed in idling operation of an internal combustion engine mounted on a vehicle by altering an intake air amount is combined with means for detecting a predetermined engine operating condition where the rotational speed of the engine is decreased or restrained by the vehicle speed and means for limiting a control signal manipulating an intake air amount under a predetermined upper limit in the case where the predetermined engine operating condition is detected so that the control system is prevented from excessively increasing an intake air amount. Preferably the operation of the limiting means as well as the operation of the feedback control is performed by a programmed microcomputer.

Abstract: A spring-loaded cartridge or capsule forms a connecting link for inclusion in the accelerator-throttle linkage of an internal combustion engine to convert such linkage to a changeable length linkage which permits an overriding governing action to close the throttle against the action of the accelerator without significant effect on the operation or feel of the accelerator. The operation or feel of the accelerator is not affected because the spring-loading of the cartridge is only slightly stronger than the normal throttle-closing spring which constantly urges the throttle toward its closed position.

Abstract: A throttle valve opening controller for applying variable retarding forces against the closing force of the throttle valve at the time of quick closing thereof depending on the running condition of the engine, comprising: a diaphragm device consisting of a diaphragm which is movable in association with the throttle valve when the throttle valve opening is smaller than the specified value, a spring for urging said diaphragm with a force smaller than the closing force of the throttle valve, and a diaphragm chamber which is formed on the rear side of said diaphragm and to which atmospheric pressure or intake vacuum immediately downstream of the throttle valve is admitted; and means for varying the leak rate of the air discharged from the diaphragm chamber of said diaphragm device at the time of quick closing of the throttle valve depending on the running condition of the engine.

Abstract: A motor brake control system for use on a motor having a motor brake retarder and a throttle fuel control is designed to respond to manual selection for sequentially retarding the selected cylinders in the motor. A transducer for sensing the speed of the motor is provided for generating a series of output pulses which access a high RPM detector and a low RPM detector. In the event that the motor exceeds a predetermined high RPM value, the brake control system activates all of the retarders to fully brake the motor. In the event that the brake retarders are on, either fully or partially, and the motor drops below a predetermined low RPM value, the brake retarders are released. Provision is made to prevent retardation of the motor as long as the throttle of the motor is being activated and retardation is further prevented after deactivation of the throttle until the fuel in the fuel delivery system has been consumed.

Abstract: This invention relates to an ignition system for an internal combustion engine. The ignition system comprises an ignition circuit to generate a spark at an ignition plug in synchronism with a rotation of the internal combustion engine. The ignition circuit may be of a capacitor discharging type or of an ignition primary current interrupting type. The ignition system further comprises an ignition preventing circuit to prevent the ignition circuit from being operated when the internal combustion engine is rotated at a speed of revolution higher than a first set value of r.p.m. and when a throttle valve operating member is quickly returned to a position at which the r.p.m. of the engine is lower than the second set value of r.p.m. which is lower than the first set value of r.p.m. The ignition preventing circuit may be adapted to fully prevent the operation of the ignition circuit. Alternatively, the ignition preventing circuit may be adapted to thin the operation of the ignition circuit.

Abstract: A fail safe device for isolating the revolution limiter from the ignition system of an internal combustion engine, in which the output stage of the revolution limiter is continuously monitored to ascertain whether or not it is absorbing ignition pulses at a speed lower than the limiting speed. In the event that the absorption of ignition pulses is taking place at a speed lower than the limiting speed, the fail safe device becomes operative upon the engine revolutions falling below a given value and causes a fuse in series with the output stage of the revolution limiter to blow, thus isolating the revolution limiter from the ignition system to allow ignition to be instantly re-established in the event of a fault occuring in the revolution limiter.

Abstract: The flow rate of intake air sucked into an internal combustion engine when a throttle valve of the engine is at the idling position is controlled so that the actual rotational speed of the engine becomes equal to a desired value. This desired value of the rotational speed of the engine is adjusted in accordance with the result of a judgement as to whether the actual rotational speed of the engine is increasing or decreasing, and the value of the actual rotational speed of the engine.

Abstract: A dash pot which functions to control a throttle throughout its movement and also functions as a throttle return spring comprising a cylindrical body in which a guide member and associated shaft are positioned with the shaft extending externally of the body and a chamber associated with the cylinder having a diaphragm defining one wall thereof. The chamber and cylinder are filled with an incompressible fluid and an orifice is provided between the chamber and the cylinder. A spring yieldingly urges the shaft inwardly. A check valve and orifice are provided in the body to restrict the flow of fluid as the guide member is moved inwardly and permit the relatively free flow of liquid from one side of the guide member to the other as the guide member and associated shaft are moved outwardly. The end of the shaft is connected to the throttle so that when the throttle is released by the operator of the vehicle, the return velocity of the throttle to idle position is controlled throughout its movement.

Abstract: A vehicle engine includes throttle stop control apparatus including means effective to store a plurality of induction passage pressure numbers corresponding to specified values of engine speed. Further apparatus measures engine speed and induction passage pressure and compares the induction passage pressure with a control reference number derived from the induction passage pressure reference number corresponding to the measured engine speed. When the throttle is in the idle position and the induction passage pressure signal exceeds the reference, a throttle stop control loop is closed on engine speed to maintain a predetermined engine idle speed. However, when the throttle is in the idle position and the induction passage pressure signal does not exceed the reference, the throttle stop control loop is closed on induction passage pressure to maintain substantially the reference pressure, whereby throttle position during vehicle coastdown is controlled according to a predetermined stored schedule.

Abstract: An internal combustion engine having a carburetor equipped with the usual throttle valve means controlling the flow of air-fuel flow to the intake manifold is provided with a normally open cut-off valve means located between the throttle valve and intake manifold to close communication therebetween when it is moved to closed position. A vehicle speed responsive device is operatively connected to the cut-off valve to move it to the closed position whenever the vehicle is coasting or moving under closed throttle valve conditions at or below a predetermined vehicle speed. In addition, there is provided a conduit between the intake manifold and the crank case with a pivoted plate clapper type check valve therein to permit flow from the crank case into the intake manifold.

Abstract: A turbine assembly is provided for use on an internal combustion engine such as a diesel engine having conventional intake and exhaust manifolds. The assembly includes a hollow section which has an inlet communicating with the exhaust manifold, and an outlet communicating with an exhaust gas entry into a chamber in which a turbine wheel is mounted. Rotatably mounted within the hollow section is a rotor which is adjustable to various selected positions. When in a first selected position, the rotor permits substantially unrestricted exhaust gas flow through the assembly. When in a second selected position, a predetermined amount of exhaust gas is diverted from the turbine wheel chamber through a bypass passageway formed in the hollow section. The end of the bypass passageway terminates downstream of the turbine wheel chamber. When in a third selected position of adjustment, the rotor effects substantial blockage of the exhaust gas flow through the assembly.

Abstract: A device for reducing noxious emissions from carburetor engines of the internal combustion type, the body of which comprises at least one main passage designed for feeding a fuel-air mixture to the engine cylinders and has an emulsion passage. The main passage accommodates a throttle valve which divides it into an upstream throttle space and a downstream throttle space, as viewed in the direction of the fuel-air mixture flow. The emulsion passage communicates with the upstream throttle space substantially in the area where the throttle valve upper edge locates when the throttle valve is in the closed position and also communicates further, as viewed in the direction of the emulsion flow, via an adjustable throttle element with a chamber which communicates via an air passage with the upstream throttle space and via a passage with the downstream throttle space. The chamber accommodates a movable element adapted to move coaxially with the passage for the purpose of closing same.

Abstract: In an emergency brake system for a vehicle having a brake booster to increase braking pressure applied to wheel brake cylinders from a master cylinder, a cut-off valve is provided within an exhaust pipe of an internal combustion engine for the vehicle and operatively connected to a manual shift lever, and a selector valve is disposed within a communication passage connecting a servo-chamber of the brake booster to an upstream of the cut-off valve in such a manner that the servo-chamber is normally communicated to a source of pneumatic pressure in response to operation of the master cylinder. The cut-off valve is normally opened when the shift lever is in a first position and is closed upon shifting the lever to a second position from the first position to create back pressure acting on the engine. The selector valve is switched-over upon shifting the lever to the second position to apply the back pressure from the exhaust pipe into the servo-chamber through the communication passage.