Re: The Duchess Project: 1940 Super 8 Convertible Sedan
Posted by HH56 On 2021/1/25 13:12:34
Condensed version of R9 Kickdown operation.
When the unit is in OD relays R1 and R2 are energized so contacts B and D in the relay box will be closed and C will be open. Contacts A in the solenoid will be closed because the plunger is extended.
When kickdown is desired, the kickdown switch is activated by the accelerator linkage and opens. That removes the ground coming from the governor to terminal 5 and causes relay 1 to drop out. Because of the way relay 2 is powered from relay 1 and goes thru the solenoid hold coil as well as some spring tension on its armature, its contact action slightly lags the other relay and remains closed for a few added milliseconds before opening.
With relay 1 turned off, solenoid is released but the mechanical motion of the plunger is slower because of its mass and being held in position by torque. Ground flows from 6 on the solenoid thru still closed contacts B and still closed contacts C to exit the relay and short out the ignition to cause the engine to lose torque and release the plunger to drop out of OD.
That short only lasts for a few milliseconds — the manual says a “few” spark pulses at driving speed. Contacts C will open with the loss of power to relay 1 when it opened to drop out the solenoid and in effect controls the length of the ign short. A few milliseconds after C opens, so does B as a safety backup contact and then finally A to permanently remove the ground to the ignition cutout circuit. Because all this is supposedly a carefully timed sequence the engine does not die. Where things go south is when for whatever reason one of the relay contacts (usually C) delays opening. Too long a delay or a ground being available when not in OD and the ign short remains long enough to cause the engine to die.
When the reason for kickdown is over, if the car is still going at speed, ground will be available thru the governor. Letting off the full accelerator to drop down to cruising speed will let the kickdown sw close again. Relay 1 will re energize, solenoid can engage if you momentarily let off the gas and you are back in OD with everything reset for the next time.
If you want to read thru the Econodrive training manual there is a professional description of the exact sequence with all the terminals and pathways described.
Attach file:
R9 Schematic copy.jpg (71.22 KB)
When the unit is in OD relays R1 and R2 are energized so contacts B and D in the relay box will be closed and C will be open. Contacts A in the solenoid will be closed because the plunger is extended.
When kickdown is desired, the kickdown switch is activated by the accelerator linkage and opens. That removes the ground coming from the governor to terminal 5 and causes relay 1 to drop out. Because of the way relay 2 is powered from relay 1 and goes thru the solenoid hold coil as well as some spring tension on its armature, its contact action slightly lags the other relay and remains closed for a few added milliseconds before opening.
With relay 1 turned off, solenoid is released but the mechanical motion of the plunger is slower because of its mass and being held in position by torque. Ground flows from 6 on the solenoid thru still closed contacts B and still closed contacts C to exit the relay and short out the ignition to cause the engine to lose torque and release the plunger to drop out of OD.
That short only lasts for a few milliseconds — the manual says a “few” spark pulses at driving speed. Contacts C will open with the loss of power to relay 1 when it opened to drop out the solenoid and in effect controls the length of the ign short. A few milliseconds after C opens, so does B as a safety backup contact and then finally A to permanently remove the ground to the ignition cutout circuit. Because all this is supposedly a carefully timed sequence the engine does not die. Where things go south is when for whatever reason one of the relay contacts (usually C) delays opening. Too long a delay or a ground being available when not in OD and the ign short remains long enough to cause the engine to die.
When the reason for kickdown is over, if the car is still going at speed, ground will be available thru the governor. Letting off the full accelerator to drop down to cruising speed will let the kickdown sw close again. Relay 1 will re energize, solenoid can engage if you momentarily let off the gas and you are back in OD with everything reset for the next time.
If you want to read thru the Econodrive training manual there is a professional description of the exact sequence with all the terminals and pathways described.
Attach file:
R9 Schematic copy.jpg (71.22 KB)
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