Usage:
introduction
The eight notch controller is intended for use on Caterpillar engines in locomotive packages. It has been used on the 3306, 3406, 3408, 3412, 3508 and 3512 family of engines in various locomotive applications.
All the engines it has been used on have had hydra-mechanical full range governors to control engine speed. In the 3508 and 3512 applications the controller is mounted on the Woodward 3161 governor.
The controller can be described as an electric, pneumatic, mechanical device for controlling the position of the speed lever on a hydra-mechanical governor. The hydra-mechanical governor them controls engine rpm based on its input shaft rotation position.
Electric
The controller requires electric signals to its 4 solenoid coils to determine which notch position (1, 2, 3, 4, 5, 6, 7 or 8) the operator is selecting.
Pneumatic
The controller uses air pressure (or lack of air pressure) in Bimba pancake cylinders to extend or collapse the cylinders.
Mechanical
The controller cylinders are stacked and assembled in a way to move the lever that turns the speed shaft of the governor when various cylinders are extended or collapsed.
NOTE: Refer to Control Logic,in this instruction, for an example of the logic used to change the eight notch American Association of Railroads (AAR) code to a binary code.
EIGHT NOTCH CONTROLLER MECHANICAL ADJUSTMENTS
5R7598 Control Group
NOTE: Low idle (also notch 1) and notch 8 are the only true adjustments possible with this control. Intermediate notches can change slightly with different starting points for notch 1, but most applications will not require attention to the middle notches.
If the axis of stud (1) and its rod end (2) are perpendicular to governor control rod (3) at its mid point travel:
* Then rpm steps between notches will be roughly equal to each other.
If this perpendicular situation exists at notch 1 position:
* Then lower notch steps will be larger than upper notch steps:
If the situation exists at notch 8:
* Then upper notch steps will be larger than lower notch steps.
NOTE: Before adjusting rod and lever lengths make certain the rod ends that face each other between Bimba cylinders (4) and (5), 3.18 mm (0.125 in) stroke and 6.35 mm (0.250 in) stroke, are tightened properly.
NOTE: Two open end wrenches may need grinding off to be thin enough to tighten this joint.
Adjustments
NOTE: The choice of spline indexing between governor control rod (3) and governor shaft can be made with considerations in the above NOTE.
1. Turn engine switch to the OFF position.
2. Remove bolt (6), nut (7) and washer (8) and check hole alignment between governor control rod (3) and rod end (2) at both idle and notch 8.
The governor control rod (3) can be used as a handle and manually moved to both ends of its travel.
The Bimba cylinders (4), (5), (9) can be extended.
* WITH air pressure to all three (to simulate notch idle and 1) .. and
* WITHOUT air pressure to all three (to simulate notch idle and 1).
NOTE: This can be done with engine STOPPED or at low idle.
If locomotive control stand is connected and air system is charged, then the cab controller can be used to extend the Bimba cylinders to check hole alignment.
3. If holes line up properly, no further adjustment is necessary.
4. Reinstall bolt (6), nut (7) and washer (8).
5. If holes do not line up, make whichever of the following adjustments as required:
NOTE: The total stroke, 22.23 mm (0.875 in), of the Bimba cylinders CANNOT be changed. Refer to Eight Notch Controller Bimba Cylinder Lengths,in this instruction, for an example of the cylinder lengths at selected notch positions.
If total Bimba stroke is too SHORT:
* The governor control rod (3) must be turned clockwise (in 1/2turn increments) for a shorter lever arm
If total Bimba stroke is too LONG:
* The governor control rod (3) must be turned counterclockwise (in 1/2turn increments) for a longer lever arm.
NOTE: The following step, adjusting fixed length of Bimba package, can be done while engine is running for final fine tuning of either idle or notch 8
Stud (1) can be turned into or out of rod end (2) to achieve the proper starting point (notch idle) or proper ending point (notch 8).
An infinite number of adjustments are available here instead of the in comparison to the 1/2turn increments used on the governor control rod.
Make the adjustments by loosening nut (10) and using flats on rod from Bimba cylinder (9) to turn stud (1)..
Final setting should be such that total stroke (dimension) of the Bimba cylinders is slightly greater than required. This is to ensure that the Bimba cylinders will not be controlling either low idle or high idle but stops inside the Woodward 3161 governor will control low idle and high idle.
EIGHT NOTCH CONTROLLER BIMBA CYLINDER LENGTH COMBINATIONS
EIGHT NOTCH CONTROLLER ELECTRICAL ADJUSTMENTS
The Controller and Woodward 3161 governor do not control excitation of the generator on any of these locomotives.
However, older Westinghouse and General Electric D.C. traction machines are generally furnished with a 3 field exciter or else use a split pole excitation design.
If equipped with a 3 field exciter or split pole excitation design the generator characteristic curve is sufficiently hyperbolic to approximate the engine horsepower capability and so special load control governing is NOT required.
Initial adjustments are required however, and even though in operation the excitation is fixed, taps on the fixed resistors can be moved during load bank testing for proper horsepower utilization at all ground speeds.
NOTE: Refer to Excitation System Schematic,in this instruction for an example of the excitation system and the resultant characteristic curve.
EXCITATION SYSTEM SCHEMATIC
Several iterations back and forth between a high voltage situation (high ground speed simulation) and a high current situation (low ground speed simulation) are generally required when doing the load bank test and commissioning a locomotive.
NOTE: The main items to remember during this iterative process are:
NEVER adjust the self field when trying to change the high amp end of the characteristic curve (the battery field's duty on that end) .. and
NEVER alter the battery field when adjusting the high voltage portion of the characteristic curve (the self field's duty on that end).
Each adjustment does effect both ends of the curve but adjustments must be made on the most effective contributor to a specific portion of the curve.
Generally the battery field adjusts the level and the self field adjusts the slope of the characteristic curve.
CONTROL LOGIC
The following chart is an example of the logic used to change the eight notch American Association of Railroads (AAR) code to a binary code.
