(or 16VDC) at many Amperes to the race car's transmission (where an internal electromagnetic solenoid located in or on the transmission energizes, which in turn positions a spool valve that directs hydraulic fluid pressure in the transmission valvebody that locks the transmission in forward and reverse gears at the same time). When the transbrake is engaged at the drag race track starting line (driver holding the pushbutton depressed), the car is held stationary regardless of how much engine power is applied to the drive line. The driver typically applies full throttle at this time, and the car remains stationary at the starting line under full engine power. When the driver sees the desired visual cue before him, the driver promptly releases his finger (or thumb) from the pushbutton. This button release opens the contacts within the pushbutton switch signaling the delay box and the delay box now begins an internal countdown. When the countdown timer reaches zero, the delay box stops current flowing to the solenoid in the transmission and that causes the spool valve to return to its normal position. With the spool valve in its normal position hydraulic fluid pressure in the transmission is removed from the reverse clutch pack (but maintained in the forward clutch pack), this causes the drag race car to "launch" (often with great thrust) from the starting line, accelerating rapidly forward toward the finish line. History Delay boxes began appearing in drag race cars in the 1980s. The early units were timers in a sheet metal box with an analog potentiometer and lock nut to establish a setpoint with no readout or feedback to the driver. These early units used a resistor / capacitor charging scheme to trigger a unijunction transistor to release an electromechanical relay. Such drag racing delay timers are very crude by today's standards. Nolen (IKE) Hamma is credited with introducing such early devices to drag racing. (currently DBA as Digital Delay, INC.) Ike Hamma is deceased. His family is assigned a patent for a type of delay timer, his son Charlie Hamma is the current president of Digital Delay Inc., a manufacturer of drag racing timers. Other entities contributed to delay box technology and also have Intellectual Property. Some of these other entities have delay box patents (Reid and Furrow), some entities did not pursue patents for their inventions even though their inventions may have predated those of known