COUPLER 1908318 - Caterpillar

Special Downshifts
During a downshift from REVERSE to NEUTRAL or from FIRST to NEUTRAL, no signal is sent to the lockup clutch solenoid. Both speeds are torque converter drive and the lockup clutch is not used.A downshift from SECOND to FIRST is a typical automatic downshift.Torque Converter Lockup
Refer to this Systems Operation module "Systems Controlled by the Transmission ECM".Engine Overspeed Protection
The Transmission ECM calculates the engine speed from the ground speed and from the transmission gear. If the engine speed increases to a predetermined level, then the Transmission ECM will upshift the transmission to one position higher than the position of the transmission gear switch. This will protect the engine from an overspeed condition. If the transmission is already in the top gear, the Transmission ECM will deactivate the lockup clutch solenoid to allow the machine to go into torque converter drive.Control Throttle Shifting
Control Throttle Shifting (CTS) is used to smooth shifting and reduce driveline stress during all automatic transmission shifts. During each transmission shift, the Transmission ECM sends a signal to the Engine ECM through the Cat Data Link. This will reduce or increase the fuel flow rate, which reduces torque during shifting. During automatic upshifts, if the throttle position is at 100 percent the Transmission ECM sends a signal to the Engine ECM tomomentarily reduce the Desired Engine Speed. During automatic downshifts, if the throttle position is at 0 percent the Transmission ECM sends a signal to the Engine ECM tomomentarily increase the Desired Engine Speed.Directional Shift Management
Directional shift management reduces torque spikes in the transmission driveline. Directional shift management reduces the energy spikes of the transmission clutch. The transmission driveline is not designed to withstand the torque converter stall. Therefore, the Transmission ECM limits the torque that is created by the engine during a torque converter stall condition. If the transmission is in REVERSE or FIRST gear, the Transmission ECM will limit the engine speed to 1600 65 rpm. The torque converter stall is the maximum amount of torque that is sent to the transmission by the torque converter.Directional shift management can occur in two ways. First, if the engine speed is above 1800 rpm and the operator shifts through the NEUTRAL position, spikes will be generated in the torque converter. Second, if the engine speed is above 1500 rpm and the operator shifts from the NEUTRAL position into FIRST gear position, or if the operator shifts from the NEUTRAL position into the REVERSE position, spikes will be generated in the torque converter.After the directional shift management occurs, the Transmission ECM signals the Engine Electronic Control Module (Engine ECM) for a reduction of fuel and for a lowering of the engine speed. The Transmission ECM then shifts to the requested gear. This reduces the stress on the driveline. This also prevents wear on the transmission and premature failures of the final drive or of the differential.The event will be recorded in the Transmission ECM as "Transmission Abuse".Top Gear Limit
The top gear limit can be programmed