SPIDER 3K8702 - Caterpillar

Introduction
For Specifications with illustrations, make reference to Specifications For 3408 & 3412 Natural Gas Engine Attachments, Form No. SENR3089. If the Specifications in Form SENR3089 are not the same as in the Systems Operation and Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.Power Take-Off Clutches
Power Take-Off Clutch (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) Plates (11) Output shaftPower take-off 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. 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 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). A PTO can have from one to three 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 left. 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.Electrical System
Three electrical systems are available to provide engine protection. In each case, engine shutoff is achieved by grounding the magneto. Each system is also capable of activating the gas shutoff valve if provided.1. For the self-powered protection system, oil pressure (OP) and water temperature (WT) protection are provided. When combined with a mechanical overspeed contactor switch (MOS), full protection is obtained. An energized-to-shutoff (ETS) gas shutoff valve (GSOV) is available which is activated by magneto voltage.2. An energized-to-run (ETR) non-auto-start-stop protection system provides OP, WT and OS (overspeed) protection. An electronic speed switch (ESS) is used for the OS protection. This system is fully independent and requires an external 24 volt power source and an energized-to-run (ETR) gas shut-off valve.3. The ETR auto-start-stop protection system is the same as