Allison ATEC/CEC transmissions use solenoids as well as spool valves to control fluid flow. Latching solenoids do not stay in an open position unless they have a constant voltage supply. Who is correct?

Allison ATEC/CEC transmissions use solenoids as well as spool valves to control fluid flow. Latching solenoids do not stay in an open position unless they have a constant voltage supply. Who is correct?

• A. Allison ATEC/CEC Transmissions Use Solenoids as Well as Spool Valves to Control Fluid Flow
• B. Latching Solenoids Do Not Stay in an Open Position Unless They Have a Constant Voltage Supply
• C. Both Statements Are Correct
• D. Neither Statement Is Correct

Answer: (A)

Allison ATEC/CEC transmissions rely on electrohydraulic control, where solenoids actuate spool valves to regulate hydraulic fluid to the gear sets. This combination of solenoids and spool valves is how shifts are produced and controlled, so statement about using solenoids and spool valves to control fluid flow is accurate. Regarding latching solenoids, they are designed to hold their position after a brief energizing pulse, so they don’t need continuous voltage to stay open. They typically use a pair of coils or a magnetic latch to switch positions and then retain that position without power. Therefore the claim that latching solenoids do not stay open unless they have constant voltage is not correct. So, the transmission indeed uses solenoids along with spool valves to control fluid flow, making that statement the true one.

Allison ATEC/CEC transmissions rely on electrohydraulic control, where solenoids actuate spool valves to regulate hydraulic fluid to the gear sets. This combination of solenoids and spool valves is how shifts are produced and controlled, so statement about using solenoids and spool valves to control fluid flow is accurate.

Regarding latching solenoids, they are designed to hold their position after a brief energizing pulse, so they don’t need continuous voltage to stay open. They typically use a pair of coils or a magnetic latch to switch positions and then retain that position without power. Therefore the claim that latching solenoids do not stay open unless they have constant voltage is not correct.

So, the transmission indeed uses solenoids along with spool valves to control fluid flow, making that statement the true one.