Injection Pump Accessories

The DB2 injection pump can be used on a variety of applications; therefore, it is available with several options as required. The options are as follows:

• The flexible governor drive is a retaining ring that serves as a cushion between the governor weight retainer and the weight retainer hub. Any torsional vibrations that may be transmitted to the pump area are absorbed in the flexible ring, therefore reducing wear of pump parts and allowing more positive governor control.
• The electrical shutoff (fig. 5-19) is available as either an energized to run (ETR) or energized to shut off (ETSO) model. In either case it will control the run and stop functions of the engine by positively stopping fuel flow to the pump plungers, thereby preventing fuel injection.
• The torque screw, used on DB2 pumps, allows a tailored maximum torque curve for a particular engine application. This feature is commonly referred to as torque backup, since the engine torque will generally increase toward the preselected and adjusted point as engine rpm decreases. The three factors that affect this torque are the metering valve opening area, the time allowed for fuel charging, and the transfer pump pressure curve.

Turning in the torque screw moves the fuel-metering valve toward its closed position. The torque screw controls the amount of fuel delivered at full-load governor speed.

If additional load is applied to the engine while it is running at full-load governed speed, there will be a reduction in engine rpm. A greater quantity of fuel is allowed to pass into the pumping chamber because of the increased time that the charging ports are open.

Fuel delivery will continue to increase until the rpm drop to the engine manufacturer’s predetermined point of maximum torque.

NOTE

Do NOT attempt to adjust the torque curve on the engine at any time. This adjustment can be done only during a dynamometer test where fuel flow can be checked along with the measured engine torque curve or on a fuel pump test stand.