SCREWDRIVER 6V7937 - Caterpillar

General Information
The fan system is composed of two groups. The groups are the hub assembly with blades and the control system. Two styles of mechanical actuated fans exist. The first style is belt driven. The second style is driven by a hydraulic motor. Both fans operate under the same principles.System Operation
Illustration 1 g00563126
(1) Hub assembly
(2) Bearing carrier assembly
(3) Belt pulley
(4) Belt pulley (accessory)
(5) Mounting bracket
(6) Identification plate
(7) Actuator
(8) Blade
(9) Control shaft
(10) Operator fork
Illustration 2 g00586242
(11) Hub assembly
(11A) Bearings
(11B) Pivot block
(11C) Pin
(11D) Collar
(11E) Blade mounting shaft
(12) Bearing end through shaft
(13) O-ring
(14) Capscrew
(15) Through shaft
(16) Spool
(17) Main shaft
(18) Bellcrank
(19) O-ring
(20) Bracket An electronic controller applies power through an electrical cable to actuator (7). The actuator rod is attached to operator fork (10), which is fastened to control shaft (9). The hex end of control shaft (9) fits into bellcrank (18), which sits in the slot of through shaft (15). Through shaft (15) is threaded onto the shifter block assembly, which consists of bearings (11A), bearing end through shaft (12) and two shifter block plates. Pivot block (11B), pin (11C), collar (11D) and blade mounting shaft (11E) are between the plates. Each blade mounting shaft has a collar and a pin. The pin is offset from the center of the blade shaft. Each pin sits in the pivot block. The pivot block fits between the two plates of the shifter block assembly.An electronic controller determines that a change in blade pitch or air flow direction is required. The controller applies power to the actuator. The actuator rod extends or the actuator rod retracts. The rod is attached to operator fork (10), which rotates control shaft (9). Control shaft (9) fits into bellcrank (18), which moves through shaft (15) and the shifter block assembly within hub (11). As the shifter block assembly moves pivot block (11B), pin (11C) and collar (11D), blade mounting shaft (11E) rotates. This increases the blade pitch or this decreases the blade pitch.