Introduction

When the words "use again" are in the description, the specification given can be used to determine if a part can be used again. If the part is equal to or within the specification given, use the part again.

When the word "permissible" is in the description, the specification given is the "maximum or minimum" tolerance permitted before adjustment, repair and/or new parts are needed.

A comparison can be made between the measurements of a worn part and the specifications of a new part to find the amount of wear. A part that is worn can be safe to use if an estimate of the remainder of its service life is good. If a short service life is expected, replace the part.

Reference: See 3208 Industrial And Marine Engine Attachments, SENR7090, for Specifications.

NOTE: For Specifications with illustrations, make reference to Specifications For 3208 Industrial And Marine Engine Attachments, SENR7090. If the Specifications in SENR7090 are not the same as in the Systems Operation and Testing & Adjusting, look at the printing date on the front cover of each book. Use the Specifications given in the book with the latest date.

Electrical System

Contactor Switch For Water Temperature

Water Temperature Contactor Switch

The contactor switch for water temperature is installed in the front cover for the engine. No adjustment to the temperature range of the contactor can be made. The element feels the temperature of the coolant and then operates the micro switch in the contactor when the coolant temperature is too high. The element must be in contact with the coolant to operate correctly. If the cause for the engine being too hot is because of low coolant level or no coolant, the contactor switch will not operate.

The contactor switch is connected to the fuel shutoff solenoid to stop the engine. The switch can also be connected to an alarm system. When the temperature of the coolant lowers to the operating range, the contactor switch opens automatically.

Pressure Switch

Pressure Switch

These type pressure switches are used for several purposes and are available with different specifications. They are used in the oil system and in the fuel system. One use of the switch is to open the circuit between the battery and the fuel shutoff solenoid after the oil pressure is below the pressure specifications of the switch. It also closes when the engine starts.

Another use of the switch is to close and activate the battery charging circuit when the pressure is above the pressure specification of the switch. It also disconnects the circuit when the engine is stopped.

Some switches of this type have three terminal connections. They are used to do two operations with one switch. They open one circuit and close another with a single switch.

Electrical Indicators And Sending Units

The electrical indicators and sending units are to operate in electrical balance. Because of this, the voltage and resistance ratings are important to get the correct indications on the indicators. See Attachment Specifications to determine which indicators and sending units can be used with each other.

Sending Unit And Indicator For Water Temperature

Sending Unit For Water Temperature

The position of the pointer is changed by the amount of electrical current that flows through the indicator. The water temperature is felt by the bulb of the sending unit. A change in water temperature causes a change of resistance in the sending unit. A change in resistance in the sending unit changes the current flow through the indicator and changes the position of the pointer.

Sending Unit And Indicator For Oil Pressure

Oil Pressure Sending Unit

The position of the pointer is changed by the amount of electrical current that flows through the indicator. The oil pressure is felt by the sending unit for the oil pressure indicator. A change in oil pressure causes a change of resistance in the sending unit. A change in resistance in the sending unit changes the current flow through the indicator and changes the position of the pointer.

Engine Protection Panel

Engine Protection Panel
(1) Oil pressure indicator. (2) Ammeter. (3) Water temperature indicator. (4) Reset button. (5) Magnetic control switch. (6) Fuse.

The engine protection panel has a magnetic control switch (5) in the panel. Pushing in and holding the reset button (4), while cranking the engine, permits the engine to start. When the oil pressure is above 105 kPa (15 psi), the engine will continue to run after reset button (4) is released.

Water Temperature Contactor Switch

Pressure Switch

The normally open contactor switch for water temperature closes when the temperature of the coolant gets higher than the setting of the switch. The oil pressure switch closes when the pressure of the oil gets lower than the setting of the switch. If either the contactor switch for water temperature or the oil pressure switch is activated, they will trip (activate) the magnetic control switch (5). This will open the circuit between the fuel shutoff solenoid and the battery. With no fuel coming to the engine, the engine will stop. A 14 ampere fuse (6) gives protection to magnetic control switch (5) if there is too much of a load put on it.

Wiring Diagrams

12 Volt Starting And Charging System With Electrical Engine Protection Panel
(1) Off, Start Switch. (2) Control panel magnetic switch. (3) Water temperature sending unit. (4) Oil pressure sending unit. (5) Starter solenoid. (6) Starter motor. (7) Hourmeter. (8) Water temperature indicator. (9) Oil pressure indicator. (10) Battery. (11) Ammeter. (12) Fuel shutoff solenoid. (13) Alternator regulator. (14) Water temperature shutoff switch (normally open). (15) Oil pressure shutoff switch (normally closed). (16) Alternator.

12 Volt Starting And Charging System With Electrical Engine Protection Panel
(1) Off, Start Switch. (2) Control panel magnetic switch. (3) Water temperature sending unit. (4) Oil pressure sending unit. (5) Starter solenoid. (6) Starter motor. (7) Hourmeter. (8) Water temperature indicator. (9) Oil pressure indicator. (10) Battery (12V). (11) Ammeter. (12) Resistor diode. (13) Water temperature shutoff switch (normally open). (14) Oil pressure shutoff switch (normally closed). (15) Fuel shutoff solenoid. (16) Alternator.

Starting And Charging System
(1) Off, Start Switch. (2) Ammeter. (3) Fuel shutoff solenoid. (4) Starter solenoid. (5) Alternator regulator. (6) Starter motor. (7) Pressure switch (normally open). (8) Alternator. (9) Battery. (10) Hourmeter.

Starting And Charging System
(1) Off, Start Switch. (2) Ammeter. (3) Fuel shutoff solenoid. (4) Starter solenoid. (5) Resistor diode. (6) Starter motor. (7) Pressure switch (normally open). (8) Alternator. (9) Battery. (10) Hourmeter.

High Water Temperature And Low Oil Pressure Alarm System
(1) Water temperature contactor. (2) Oil pressure switch (normally closed). (3) Battery. (4) Toggle switch. (5) Signal light. (6) Horn.

NOTE: Toggle switch (4) can be in the circuit for a way to turn off horn (6).

Tachometer Wiring Diagram (One Tachometer)
(1) Tachometer. (2) Tachometer sending unit.

Power Takeoff Clutches

Power Takeoff Clutches (Typical Illustration)
(1) Ring. (2) Driven discs. (3) Link assemblies. (4) Lever. (5) Key. (6) Collar assembly. (7) Nut. (8) Yoke assembly. (9) Hub. (10) Drive plates. (11) Output shaft.

Power takeoff clutches (PTO's) are used to send power from the engine to accessory components. For example, a PTO can be used to drive an air compressor or a water pump.

The PTO is driven by a ring (1) that has spline teeth around the inside diameter. The ring can be connected to the front or rear of the engine crankshaft by an adapter.

NOTE: On some PTO's located at the rear of the engine, ring (1) is a part of the flywheel.

The spline teeth on the ring engage with the spline teeth on the outside diameter of driven discs (2). When lever (4) is moved to the ENGAGED position, yoke assembly (8) moves collar assembly (6) in the direction of the engine. The collar assembly is connected to four link assemblies (3). The action of the link assemblies will hold the faces of driven discs (2), drive plates (10) and hub (9) tight together. Friction between these faces permits the flow of torque from ring (1), through driven discs (2), to drive plates (10) and hub (9).

Spline teeth on the inside diameter of the plates drive the hub. The hub is held in position on the output shaft (11) by a taper, nut (7) and key (5).

NOTE: A PTO can have one or two driven discs (2) with a respective number of plates.

When lever (4) is moved to the NOT ENGAGED position, yoke assembly (8) moves collar assembly (6) to the right. The movement of the collar assembly will release link assemblies (3). With the link assemblies released, there will not be enough friction between the faces of the clutch assembly to permit a flow of torque.