How To Change Gear Drive On Cummins Pt Pump

Oct. 11, 2017

When information technology comes to Cummins generator , it is well known that the gensets have good quality, depression fuel consumption, low noise, large output power and reliable performance. The reliable stability, economy, power functioning, durability and environmental safety is welcomed by customers.

In last commodity, we talk about CCEC Cummins diesel engines operating principles. Well, in this article, you lot volition learn what are the major components of its PT Fuel System.

Fuel System

The PT fuel organisation is used exclusively on Cummins Diesels. The identifying letters, "PT" are an abbreviation for "pressure level-time".

The operation of the Cummins PT Fuel System is based on the principle that the volume of liquid flow is proportionate to the fluid pressure, the time allowed to flow and the passage size through which the liquid flows. To apply this simple principle to the Cummins PT Fuel System, it is necessary to provide:

1. A fuel pump.

2. A means of decision-making pressure of the fuel being delivered past the fuel pump to the injectors then individual cylinders will receive the correct corporeality of fuel for the ability required of the engine.

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Fig.5-1. Fuel menses schematic N/NT-855 Engine

1). PT (TYPE Grand) FUEL PUMP

2). SHUT-Downwardly VALVE

3). FUEL CONNECTOR

iv). INJECTOR

v). INJECTOR RETURN

6). FROM TANK

7). FUEL FILTER

3. Fuel passages of the proper size and type so fuel will be distributed to all injectors and cylinders with each pressure under all speed and load conditions.

iv. Injectors to receive low-pressure from the fuel pump and deliver it into the private combustion chambers at the right fourth dimension, in equal quantities and proper condition to burn.

The PT fuel system consists of the fuel pump, supply lines, drain lines, fuel passages and injectors.

Fuel Pump

The fuel pump is coupled to the fuel pump bulldoze which is driven from the engine gear train. Fuel pump main shaft in turn drives the gear pump, governor and tachometer shaft assemblies.

Fuel injection pumps must be supplied with fuel nether force per unit area because they have bereft suction ability. All diesel injection systems crave a supply pump transfer fuel from the supply tank through the filters and lines to the injection pump.

Gear Pump And Pulsation Damper

The gear pump is driven past the pump main shaft and contains a single set of gears to choice up and deliver fuel throughout the fuel system. Inlet is at the rear of the gear pump. A pulsation damper mounted to the gear pump contains a steel diaphragm which absorbs pulsations and smooths fuel flows through the filter screen and to the governor assemblies.

Throttle

The throttle provides a means for the operator to manually control engine speed above idle as required by varying operating weather condition of speed and load.

In the fuel pump, fuel flows through the governor to the throttle shaft. At idle speed, fuel flows through the idle port in the governor butt, by the throttle shaft. To operate above idle speed, fuel flows through the main governor barrel port to the throttling hole in the shaft.

PT(type Thou) VS Fuel Pump

The PT (blazon G) VS fuel pump, is made upwards of iv main units; the gear pump, standard governor, throttle and a VS (Variable Speed) governor.

Governors

The "Standard" governor is actuated by a system of springs and weights, and has 2 functions:

i. The governor maintains sufficient fuel for idling with the throttle control in idle position.

2. It cuts off fuel to the injectors in a higher place maximum rated rpm.

During functioning between idle and maximum speeds, fuel flows through the governor to the injectors. This fuel is controlled by the throttle and limited by the size of the idle leap plunger counter bore. When the engine reaches governed speed, the governor weights movement to governor plunger, and fuel passages to the injectors are shut off. At the same time another passage opens and dumps the fuel back into the main pump trunk.

In this fashion, engine speed is controlled and express past the govern or regardless of throttle position.

The VS governor, in the upper portion of the fuel pump housing, operates in series with the standard governor to permit operation at whatsoever desired (near constant) speed setting inside the range of the standard governor. Speed can exist varied with the VS speed control lever, located at top of pump. This pump gives surge free govern ring throughout the engine speed range with a speed droop smaller than the standard governor and is suited to the varying speed requirements of power take off, etc.

Note: When operating the PT(type G) VS fuel pump at whatsoever desired abiding speed, the VS governor lever should be placed in operating position and the throttle locked in full open up position to allow a full menses of fuel through the standard governor.

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PT (tyep D) Injectors

The injector provides a means of introducing fuel into each combustion bedchamber. It combines the acts of metering, timing and injection. Principles of functioning are the aforementioned for Inline and 5-engines but injector size and internal design differs slightly.

Fuel supply and drain flow are accomplished through internal drillings in the cylinder heads. A radial groove around each injector mates with the drilled passages in the cylinder head and admits fuel through an adjustable orifice plug in the injector body. A fine mesh screen at each inlet groove provides final fuel filtration.

The fuel grooves around the injectors are separated by 0-rings which seal against the cylinder head injector bore. This forms a leak-proof passage between the injectors and the cylinder caput injector diameter surface.

Fuel flows from a connection atop the fuel pump shutdown valve through a supply line into the lower drilled passage in the cylinder head. A second drilling in the head is aligned with the upper injector radial groove to drain away excess fuel. A fuel drain allows render of the unused fuel to the fuel tank.

The injector contains a ball check valve. Ad the injector plunger moves downwardly to encompass the feed opening, an impulse pressure wave seats the ball and at the same fourth dimension traps a positive corporeality of fuel in the injector loving cup for injection. As the continuing downward plunger movement injects fuel into the combustion chamber, information technology besides uncovers the drain opening and the ball rises from its seat. This allows costless flow through the injector and out the bleed for cooling purposes and purging gases from the cup.

Fuel Lines, Connections And Valves

Supply And Drain Lines - Fuel is supplied through lines to cylinder heads. A mutual drain line returns fuel not injected, to supply tank.

Connections - Fuel connectors are used betwixt the Inline engine cylinder heads to bridge the gap between each supply and drain passage.

Shut-Down Valve - Either a manual or an electric shut-downwardly valve is used on Cummins Fuel Pumps.

Cummins fuel pump.jpg

Fig. five-2, Fuel pump transmission override knob

Attending: With a manual valve, the control lever must exist fully clockwise or open up to permit fuel flow through the valve.

With the electric valve, the transmission control knob must be fully counterclockwise to permit the solenoid to open up the valve when the "switch key" is turned on. For emergency performance in case of electrical failure, turn transmission knob clockwise to let fuel to menstruum through the valve.

No matter it is engine's fuel arrangement or other parts, it is very necessary and important to know near the related knowledge if you want to prolong the generator set service life. Also, familiar with the performance, it is convenient to do the maintenance in the future.