Vehicular engine brake assembly

Claim 2

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground engaging wheel, an internal combustion engine mounted on the frame, means forming a driving connection between the internal combustion engine and the rear ground engaging wheel, said engine having a housing, a piston slidably mounted in the housing and forming a compression chamber in the housing, said housing having a hole opening into the portion of the combustion chamber which is not swept by the piston, intake means external of said housing for supplying combustible gases to said combustion chamber, a braking device mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole in said housing, said body having a flow passage extending longitudiNally of the body and opening through the portion of the body extending into said hole and being in communication with said combustion chamber, said body being formed with an annular valve seat on said portion of said body extending into the hole and circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat to thereby permit gases from the combustion chamber to pass into said flow passage when said valve member is in an open position and to prevent the passage of the gases from the combustion chamber into the flow passage when said valve member is in a closed position, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged to a closed position, said body having at least one additional flow passage therein, means exclusively external of said housing and coupling said additional flow passage to said intake means in such a manner that said additional flow passage is exposed to atmospheric pressure, a control cable having one end disposed in the vicinity of the handle bars and having the other end coupled to the braking device and means connected to the end of the control cable disposed in the vicinity of the handle bars for causing operation of the control cable to effect movement of the valve member towards an open position against the force of the yieldable means to permit gasses being compressed in the combustion chamber during the compression stroke of the piston to escape through the first named flow passage, the additional flow passage and into the intake means whereby such gases which are discharged during braking of the motorcycle will be sucked back into the combustion chamber during the return stroke of the piston.

Claim 3

In a braking device for use with a motorcycle driven by two-cycle internal combustion engine of the type having a housing, a piston mounted in the housing and forming a compression chamber in said housing with the housing having a hole therein extending therethrough and in communication with the combustion chamber and actuatable by the use of the control means accessible to the operator of the motorcycle, said device comprising a body adapted to be secured to said housing so that a portion of said body is adapted to extend into said hole, said body having a flow passage therein extending longitudinally thereof and opening through said portion of the body whereby said flow passage is in communication with said combustion chamber when said body is mounted on said housing, said body having an annular valve seat formed on said portion of the body circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases from the combustion chamber can pass into the flow passage and when said valve member is in a closed position gases from the combustion chamber cannot pass into said flow passage, spring means, means retaining said spring means so that it is carried by the body concentric to the valve stem and supplies a force to the valve stem so that the valve member is yieldably urged to a closed position, said body having at least one additional flow passage opening to the atmosphere and in communication with said first named flow passage whereby gases flowing from said combustion chamber into said first named flow passage can flow to the atmosphere, check valve means within the body and movable between open and closed positions with respect to said additional flow passage and operable independently of the valve member and in an open position permitting the flow of gases from the first named flow passage and the additional flow passage to the atmosphere and in a closed position preventing flow of gases from the atmosphere into said first named flow passage, said check valve means including additional spring means concentric with said valve stem and exerting a force independent of said first named spring means and means connected to said valve stem and adapted to be connected to said control means whereby the valve member may be moved to an open position against the force of the spring means.

Claim 4

In a braking device for use with a motorcycle driven by two-cycle internal combustion engine of the type having a housing, a piston mounted in the housing and forming a compression chamber in said housing with the housing having a hole therein extending therethrough and in communication with the combustion chamber and actuatable by the use of the control means accessible to the operator of the motorcycle, said device comprising a body adapted to be secured to said housing so that a portion of said body is adapted to extend into said hole, said body having a flow passage therein extending longitudinally thereof and opening through said portion of the body whereby said flow passage is in communication with said combustion chamber when said body is mounted on said housing, said body having an annular valve seat formed on said portion of the body circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases from the combustion chamber can pass into the flow passage and when said valve member is in a closed position gases from the combustion chamber cannot pass into said flow passage, spring means, means retaining said spring means so that it is carried by the body concentric to the valve stem and supplies a force to the valve stem so that the valve member is yieldably urged to a closed position, said body having at least one additional flow passage opening to the atmosphere and in communication with said first named flow passage whereby gases flowing from said combustion chamber into said first named flow passage can flow to the atmosphere, check valve means within the body and movable between open and closed positions with respect to said additional flow passage and operable independently of the valve member and in an open position permitting the flow of gases from the first named flow passage and the additional flow passage to the atmosphere and in a closed position preventing flow of gases from the atmosphere into said first named flow passage, said check valve means including additional spring means concentric with said valve stem and exerting a force independent of said first named spring means and means connected to said valve stem and adapted to be connected to said control means whereby the valve member may be moved to an open position against the force of the spring means.

Claim 5

A device as in claim 2 wherein said body is formed with additional valve seat means circumscribing said additional flow passage and wherein said check valve means includes a valve member slidably mounted on said valve stem for movement between open and closed positions with respect to said additional valve seat means and wherein said additional spring means engages said additional valve member for yieldably urging said additional valve member towards a closed position.

Claim 6

A device as in claim 3 wherein said additional spring means exerts a force on said additional valve member which is less than the force exerted by said first named spring means on said first named valve member.

Claim 7

A device as in claim 3 wherein said body is formed and said first named and additional spring means are positioned with respect to said body so there is no significant contact between said first named and additional spring means and the gases passing from the combustion chamber through said first named and additional flow passages to the atmosphere.

Claim 8

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve sTem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage, said check valve means including an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve means, said check valve means including additional spring means carried by the body yieldably urging said additional valve member to a closed position, said additional spring means applying force to said additional valve member which is significantly less than the force supplied by the first named spring means to said first named valve member, said body being formed with a well carried by the body, said additional spring means being disposed in said well, said additional valve member having a cylindrical portion adapted to seat in said well to substantially seal said well from said gases when said additional valve member is in an open position, said body having a chamber formed about said additional valve member which is open to the additional flow passage, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 9

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve sTem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage, said check valve means including an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve means, said check valve means including additional spring means carried by the body yieldably urging said additional valve member to a closed position, said additional spring means applying force to said additional valve member which is significantly less than the force supplied by the first named spring means to said first named valve member, said body being formed with a well carried by the body, said additional spring means being disposed in said well, said additional valve member having a cylindrical portion adapted to seat in said well to substantially seal said well from said gases when said additional valve member is in an open position, said body having a chamber formed about said additional valve member which is open to the additional flow passage, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 10

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body concentric with said valve stem and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body including additional spring means concentric with said valve stem operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said chEck valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said first named spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said first named and additional spring means and said body being formed so that there is no significant contact between said first named and additional spring means and the gases passing from the combustion chamber through the first named and additional flow passages to the atmosphere, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 11

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body concentric with said valve stem and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body including additional spring means concentric with said valve stem operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said chEck valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said first named spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said first named and additional spring means and said body being formed so that there is no significant contact between said first named and additional spring means and the gases passing from the combustion chamber through the first named and additional flow passages to the atmosphere, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 12

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage and wherein said check valve means includes an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve seat means, said check valve means including additional spring means carried by the body and yieldably urging said additional valve member to a closed position, said additional spring means supplying a force to said additional valve member which is significantly less than the force supplied by said first named spring means to said first named valve member, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against the force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 13

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage and wherein said check valve means includes an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve seat means, said check valve means including additional spring means carried by the body and yieldably urging said additional valve member to a closed position, said additional spring means supplying a force to said additional valve member which is significantly less than the force supplied by said first named spring means to said first named valve member, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against the force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 14

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage, said check valve means including an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve seat means, said check valve means including additional spring means carried by the body and yieldably urging said additional valve member to a closed position, said additional spring means applying a force to said additional valve member which is significantly less than the force applied by said first named spring means to said first named valve member, said first named additional spring means being mounted so that the movement of said first named valve member does not affect the force exerted by said additional spring means, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against the force of the first named spring means so that braking is applied to the motorcycle by said engine.

Claim 15

In a motorcycle having a supplemental engine braking device, a frame, front and rear ground-engaging wheels carried by the frame, handle bars carried by the frame for guiding the front ground-engaging wheel, an internal combustion engine mounted on the frame, means forming a drive connection between the internal combustion engine and the rear ground-engaging wheel, said engine having a housing, a piston slidably mounted in said housing and forming a compression chamber in the housing, said housing having a hole therein opening into the combustion chamber in the portion thereof which is not swept by the piston, the improvement comprising a braking device adapted to be mounted on said housing and extending into said hole, said braking device including a body having a portion thereof extending into said hole, said body having a flow passage extending longitudinally thereof and opening through said portion into said combustion chamber, said portion of said body being formed within an annular valve seat circumscribing said flow passage, a valve member having a valve stem, valve stem guiding means carried by the body for slidably receiving the valve stem to permit said valve member to move between open and closed positions with respect to said valve seat whereby when said valve member is in an open position gases can escape from said combustion chamber into said flow passage and when said valve member is in a closed position gases from said combustion chamber are prevented from escaping into said flow passage, spring means, means retaining said spring means so that said spring means is carried by the body and supplies a force to the valve stem so that the valve member is yieldably urged into a closed position, said body having at least one additional flow passage therein opening to the atmosphere in communication with said flow passage whereby gases passing from said combustion chamber into said first named flow passage can flow solely to the atmosphere, yieldable check valve means carried by the body operable independently of the valve member and movable between open and closed positions with respect to said additional flow passage whereby in the open position of said check valve means gases from said first named flow passage can escape through said additional flow passage to the atmosphere and in the closed position, gases from the atmosphere are prevented from flowing through the additional flow passage into said first named passage, said valve stem guiding means carried by the body being disposed above said first named and additional flow passages and being separate from said check valve means, said spring means being disposed exteriorly of said valve stem guiding means and having at least a portion thereof extending beyond said valve stem guiding means, said body being provided with additional valve seat means circumscribing said additional flow passage, said check valve means including an additional valve member slidably mounted on said valve stem and movable between open and closed positions with respect to said additional valve seat means, said check valve means including additional spring means carried by the body and yieldably urging said additional valve member to a closed position, said additional spring means applying a force to said additional valve member which is significantly less than the force applied by said first named spring means to said first named valve member, said first named additional spring means being mounted so that the movement of said first named valve member does not affect the force exerted by said additional spring means, a control member adapted to be disposed in the vicinity of the handle bars and a control cable connecting said control member to said braking device whereby upon operation of said control member by the operator of the vehicle, said valve member is moved to an open position against the force of the first named spring means so that braking is applied to the motorcycle by said engine.