Levers and Pins.—On these old engines the pump levers and pins are generally badly worn. An engineer, when this condition exists, should promptly ream the pin bearings to a larger diameter and turn up new pins to conform. For this work an expansion reamer is desirable in order to handle all the various size pin bearings.
Busch-Sulzer Type B Diesel Fuel Pump.—While the mechan ical details differ, the Busch-Sulzer Type B Diesel's fuel pump follows the same principle as does the American engine just dis cussed. Figure 136 is a cross-section of the Type B pump, show ing one plunger. This is along designs adopted by the majority of European and English Diesel builders. In this construction the plunger A is driven by an eccentric B keyed to the vertical governor shaft C. The suction valve is mechanically operated by a dog F, which swings on an eccentric G. This eccentric is mounted on a small shaft controlled by the governor K through a linkage J and bell-crank I shown. The suction valve plunger D is also driven by a fixed eccentric E on the vertical governor shaft, being 180 degrees behind the pump plunger eccentric. In Fig. 136 the pump plunger is at the e ad of the delivery stroke while the suction valve plunger is at the extreme inner position. As the governor shaft revolves, at one-half engine speed, the pump plunger moves to the end of its suction stroke; the suction plunger moves outward, lifting the suction valve off its seat ;this allows the fuel to enter the pump cavity. As the pump plunger reverses and moves on its delivery stroke, the suction valve re mains open, the oil flowing back into the suction line. At a stated point in the pump plunger travel, the suction plunger moves out of contact with the dog F; the valve now closes and the oil is forced out through the discharge valve. If the load decreases, the rising governor sleeve shifts the center of the eccen tric dog bearing. This allows the valve plunger to remain in contact with the suction valve for a longer interval, which per mits more of the fuel charge to flow back into the suction line.
On these engines there is a pump plunger and suction valve plunger for each engine cylinder. It is possible to use only one suction valve plunger, but this individual suction valve mechan ism offers opportunity for a closer adjustment of the functioning of each pump. On some of the four-cylinder engines the four plungers are arranged in a single row, while on others there are two sets of two plunger cavities each, placed end to end with the valve block in the center.
This fuel pump gives the closest possible speed regulation while the reaction on the governor is at a minimum. The re sistance offered to the movement of the governor sleeve consists of the suction valve spring compression.
Filling the Fuel facilitate charging the pump and discharge line with oil, an eccentric shaft L is provided. This shaft is rotated by means of a hand lever, and, by so doing, the dog F is raised to its maximum lift. This lifts both the suction and discharge valves.
Stopping the less angular travel of the eccentric shaft L lifts only the suction valve. This relieves the pumps of the oil charge, and the engine stops from the lack of fuel.
Setting Pump four plunger puinps deliver the fuel to the four cylinders on all four cycles, i.e., suction, compres sion, expansion and exhaust strokes. In timing the pump and the suction valve opening, the engine is slowly turned over, and the inner and outer dead-centers of the pump plunger eccentric are marked on the plunger. The engine is then turned over until the pump plunger is inch from its discharge dead-center. The suction valve plunger, or regulating plunger, has at this point moved away from the dog or bell-crank, which leaves its contact with the suction valve stem. The suction valve plunger should be adjusted to give a clearance of .002 inch between the dog and valve stem when the pump plunger is in the position mentioned. In setting the valve, the governor collar must be central. In a two-plunger pump this means that the collar must be in the mid-point of its travel, while with a four-plunger pump the collar must be on its bottom position; to obtain the latter the governor springs must be removed.
Pump engineer need give but slight attention to the pump other than to the valves. Both the suction and discharge valves wear rapidly, as may be expected of any type of pump valve when dirty oil is handled. In regrinding, emery flour should be used, placing a very small quantity on the valve face. In some engines the discharge valve spring continually breaks. It is hard to determine the cause; at times a lighter spring relieves the trouble while on other pumps a heavier spring is required.