Engine overspeed control of retarder

In a hydrodynamic retarder;

• a drive member;
• hydrodynamic retarder means having a stator and a rotor operatively connected to said drive member in a retarder chamber with an inlet passage and an outlet passage operative on the supply of fluid to said inlet passage and chamber to retard said rotor;
• a source of fluid under pressure;
• control valve means having a valve member movable between a retarder off position and a retarder full on position and stop means to limit movement of the valve member beyond each position and being operative in said retarder off position to empty said retarder chamber and in said retarder full on position to connect said source to said retarder chamber to fill said retarder chamber;
• speed governor means operatively connected to said drive member operative in response to a predetermined overspeed to provide an overspeed pressure signal;
• control means having a manual actuator member movable between a manual retarder off position and a manual retarder on position and linkage means connecting said manual actuator member to said valve member and including motor means having a pair of relatively movable motor members movable between an automatic retarder off position and an automatic retarder on position and having motor biasing means to normally apply a force to position said motor members in said automatic retarder off position and connected to said governor means for operation in response to said overspeed pressure signal to move said motor members to said automatic on position and positive stop means to limit movement in said automatic retarder off position, a linkage means actuator portion connecting said manual actuator member to one motor member for conjoint movement of said manual actuator member and said one motor member and a linkage means valve portion connecting the other motor member to said valve member for conjoint movement of said other motor member and said valve member, linkage biasing means biasing said manual actuator member to said manual retarder off position with less force than said motor biasing means and actuator stop means to limit movement of said manual actuator member in said manual retarder off position and said control means operative, when said motor means is biased by said motor biasing means to said automatic retarder off position, in response to manual force moving said manual actuator member from said manual retarder off position to said manual retarder on position against said manual biasing means to act through said linkage means and said motor means and its positive stop means to positively manually move said valve member from said retarder off position to said retarder full on position and on relaxation of said manual force to permit said linkage biasing means to return said manual actuator member from said retarder full on position to said retarder off position under the force of said linkage biasing means transmitted by said linkage means and said motor means and said motor biasing means to move said valve member to retarder off position and operative when said motor means is moved by said overspeed pressure signal to said automatic retarder on position to move said valve member to said retarder full on position against the reaction of said manual actuator member in its manual retarder off position against said actuator stop means or any manually held partial retarding position to provide the reaction for the motor means to move said valve member from retarder off or any partial retarding position to the full retarder on position.

In a power train;

• a housing;
• an input member for drive by an engine and an output member for driving a load;
• a hydrodynamic retarder having a stator providing a bladed stator chamber and a bladed rotor drive connected to said output member for retarding and rotatably mounted in said stator chamber for hydrodynamic retarding when fluid is supplied to said stator chamber;
• retarder control valve means having a movable valve element and return bias means to bias the valve element for limited distance movement from a retarder full on position to a retarder off position connected to respectively fill and empty said chamber;
• governor means operatively connected to one of said members operative to provide a pressure signal in response to a predetermined overspeed;
• retarder apply means having an actuator member mounted for limited movement between a retarder off position and a retarder full on position, a return spring biasing said actuator member to the retarder off position;
• fluid motor means having a pair of relatively movable walls forming a chamber therebetween, one wall being connected to said actuator member for conjoint movement with said actuator member, the other wall being mounted for limited relative movement with respect to said one wall through a distance between a retarder automatic on position and a retarder automatic off position and operatively connected to said valve element for conjoint movement with said valve element from retarder on position to retarder off position, a return and force transmitting spring biasing said walls to the retarder automatic off position and a motor chamber between said walls selectively pressurized to move one wall against said return and force transmitting spring to said retarder automatic on position relative to the other wall, said governor means operative in the absence of said governor signal to connect said motor chamber to exhaust to permit said return and force transmitting spring to position said motor means in said retarder automatic off position and said actuator member in the retarder on and off positions acting through said motor means to respectively position said retarder control valve means in retarder on and off positions and motor means having restricted opening means and being operative in response to said signal to move said motor means at a slow rate controlled by said restricted opening means to the retarder automatic on position to move said retarder control valve means at a controlled rate to said retarder full on position to automatically apply said retarder in response to overspeed.

In a power train;

• a housing;
• an input for drive by an engine and an output member for driving a load;
• hydrodynamic retarder means having a retarder chamber with a bladed stator and a bladed rotor drive connected to said output member for retarding and having an inlet passage and an outlet passage for hydrodynamic retarding when fluid is supplied to said retarder chamber;
• a source of fluid under pressure;
• retarder control valve means having a movable valve element and return bias means to bias the valve element for limited distance movement from a retarder full on position to a retarder off position and connected to said source, chamber inlet and outlet passages operative with said valve element in said retarder off position to connect said chamber outlet passage to exhaust and to block said chamber inlet passage and operative on movement of said valve element to retarder full on position to connect said source to said chamber inlet passage for full retarding;
• governor means operatively connected to one of said members operative to provide a pressure overspeed signal in response to a predetermined overspeed;
• retarder apply means having a manual actuator member movable between a retarder off position and a retarder full on position, a return spring biasing said apply means to the retarder off position, first stop means limiting actuator member movement in the retarder off position, fluid motor means having a cylinder having an end closing wall at one end and an open wall at the other end and said cylinder operatively connected to said actuator member for bodily movement by said actuator member and conjoint movement of said cylinder and said actuator member, a piston in said cylinder mounted for movement relative to said cylinder between a retarder automatic on position and a normal retarder automatic off position and operatively connected to said valve element for conjoint movement of said piston and said valve element, a return and force transmitting spring seated on said cylinder biasing said piston to the normal retarder automatic off position, second stop means limiting piston movement in said normal retarder automatic off position and a cylinder chamber between said piston and closing wall connected to said governor means and operative in response to said pressure signal to more said piston against said return and force transmitting spring to said retarder automatic on position relative to said cylinder operative in the absence of said governor pressure signal to permit said return and force transmitting spring to position said piston in said retarder automatic off position relative to said cylinder and said retarder apply means in the retarder on and off positions acting to transmit force through and bodily move said fluid motor means, in the apply direction through said second stop means and in the release direction through said return and force transmitting spring, to respectively position said retarder control valve means in retarder on and off positions and operative in response to said pressure signal to move said piston against said return and force transmiting spring relative to said cylinder to the retarder automatic on position to move said retarder control valve means to said retarder full on position to automatically apply said retarder in response to overspeed against the reaction of said manually actuated member against said first stop means in retarder off position or any manually held position.

In a power train;

• a housing;
• an input member for drive by an engine and an output member for driving a load;
• hydrodynamic retarder means having a bladed stator fixed on said housing and a bladed rotor rotatably mounted drive connected to said members for retarding and to form a retarder chamber having an inlet passage and an outlet passage for hydrodynamic retarding when fluid is supplied to said retarder chamber inlet passage and operative to pump fluid to said outlet passage;
• a cooler having an inlet passage and an outlet passage;
• a source of fluid under pressure connected to said cooler inlet passage;
• an exhaust;
• retarder control valve means having a movable valve element providing a variable restriction, return bias means to bias the valve element with a low force and valve stop means for limited distance movement from a retarder full on position to a retarder off position and connected to said retarder chamber inlet and outlet passages, said cooler inlet and outlet passages and said exhaust operative with said valve element in said retarder off position to connect said chamber outlet passage to exhaust to block said chamber inlet passage and to open said variable restriction and connect said cooler outlet through said open variable restriction to exhaust and operative on movement of said valve element to retarder full on position to connect said chamber outlet passage to said cooler inlet passage and said cooler outlet passage to said chamber inlet passage and progressively close said variable restriction for increasing flow to said chamber for increase to full retarding;
• governor means operatively connected to said input member operative to provide an overspeed signal in response to a predetermined input member speed at a predetermined engine overspeed above the governed speed and having hysteresis to maintain said overspeed signal down to a speed just below said governed speed;
• a source of air under pressure;
• retarder apply linkage means having a manual actuator member mounted for movement, actuator member stop means limiting movement to the same limited distance movement as said valve element between a retarder off position and a retarder full on position, a return spring biasing said linkage means with an intermediate force to the retarder off position;
• air cylinder motor means having a cylinder having an end closing wall at one end and an open spring seat wall with a restricted opening at the other end and connected to said actuator member for movement with said actuator member, a piston in said cylinder mounted for movement relative to said cylinder, piston cylinder stop means limiting movement to the same limited distance as said valve element between a retarder automatic on position and a normal retarder automatic off position and having a piston rod extending through said closing wall in slidable sealed relation and connected to said valve element, a return and force transmitting motor spring seated on said open spring seat wall and biasing said piston with a high force to the normal retarder automatic off position to shorten said linkage means and a cylinder chamber between said piston and closing wall selectively pressurized to move said piston against said return and force transmitting spring to said retarder automatic on position relative to said cylinder to elongate said linkage means and an air valve means having an exhaust and connected to said cylinder chamber, said air source and said governor means and operative in the absence of said governor overspeed signal to connect said cylinder chamber to exhaust to permit said return and force transmitting spring to position in said retarder automatic off position relative to said cylinder and said retarder apply linkage means in the retarder on and off positions acting through said air cylinder means, the positive stop means transmitting manual apply force and the high force motor spring transmitting the intermediate force from the return spring to respectively manually position said retarder control valve means in retarder on and off positions and operative in response to said overspeed signal to connect said air source to said cylinder chamber to move said piston against said return and force transmitting spring at a slow rate controlled by said restricted opening relative to said cylinder to the retarder automatic full on position to move said retarder control valve means at a controlled rate to said retarder full on position to automatically fully apply said retarder in response to overspeed with said apply member in the retarder off position or any manual held position providing the reaction.