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A viscous fluid coupling includes a housing rotatably supported to a drive shaft of an engine. An operation plate set in the housing divides a space of the housing into a reservoir and an operation chamber. The operation plate has a communication hole communicating the reservoir and the operation ch

A viscous fluid coupling includes a housing rotatably supported to a drive shaft of an engine. An operation plate set in the housing divides a space of the housing into a reservoir and an operation chamber. The operation plate has a communication hole communicating the reservoir and the operation chamber. A rotor fixed to the drive shaft is disposed in the operation chamber. A valve mechanism installed to the operation plate to close and open the communication hole according to ambient temperature of the housing. A driven wheel fixed to the housing is located between the operation plate and the rotor. A torque transmitting section includes a first annular projection concentrically formed on the driven wheel and a plurality of second annular projections concentrically formed on the rotor. The first annular projections are overlappedly adjacent to the second annular projections so as to establish fluid coupling therebetween through the viscous fluid.

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A viscous fluid coupling includes a housing rotatably supported to a drive shaft of an engine. An operation plate set in the housing divides a space of the housing into a reservoir and an operation chamber. The operation plate has a communication hole communicating the reservoir and the operation ch

A viscous fluid coupling includes a housing rotatably supported to a drive shaft of an engine. An operation plate set in the housing divides a space of the housing into a reservoir and an operation chamber. The operation plate has a communication hole communicating the reservoir and the operation chamber. A rotor fixed to the drive shaft is disposed in the operation chamber. A valve mechanism installed to the operation plate to close and open the communication hole according to ambient temperature of the housing. A driven wheel fixed to the housing is located between the operation plate and the rotor. A torque transmitting section includes a first annular projection concentrically formed on the driven wheel and a plurality of second annular projections concentrically formed on the rotor. The first annular projections are overlappedly adjacent to the second annular projections so as to establish fluid coupling therebetween through the viscous fluid. t of said spring and the urging of said spring into contact with said pawls. 8. In a ratcheting tool of the type having a handle, a gear rotatably disposed on said handle, two pawls disposed in said handle and being movable toward and away relative to said gear and being arranged to be in driving engagement with said gear upon movement toward said gear, and an actuator movably mounted on said handle and being arranged to be, drivingly related to said pawls for moving said pawls away from said gear and thereby out of engagement with said gear, the improvement comprising: a spring having a length with two terminal ends and an intermediate portion, said handle having two spaced apart walls free of any curvature and said walls and additional means on said handle engagable with said intermediate portion to movably confine said intermediate portion toward and away relative to said gear, means on said handle for restraining said spring against movement toward said pawls, and said two terminal ends extending from said intermediate portion and into contact with respective ones of said pawls for urging said pawls into engagement with said gear. 9. The ratcheting tool as claimed in claim 8, wherein: said intermediate portion and said walls are planar in their respective extents. 10. The ratcheting tool as claimed in claim 8, wherein: said handle has a longitudinal axis and said gear is rotatable about said axis, said two pawls are radially spaced from said axis and are disposed on a circle coaxial with said axis, and said two pawls and said walls are all three at least approximately equally spaced from each other along said circle. 11. The ratcheting tool as claimed in claim 8, including: said handle has two surfaces fixed thereon, and said spring has two leg portions extending from said intermediate portion to respective ones of said terminal ends and said leg portions are disposed to respectively abut said handle surfaces to place said spring under spring tension and thereby enhance both the confinement of said spring and the urging of said spring into contact with said pawls. 12. In a ratcheting tool of the type having a handle with a longitudinal axis, a gear rotatably disposed on said handle along said axis for driving a tool bit, two pawls disposed in said handle and being movable toward and away relative to said gear and being arranged to be in driving engagement with said gear upon movement toward said gear, and an actuator movably mounted on said handle and being arranged to move said pawls away from said gear and thereby out of engagement with said gear, the improvement comprising: a spring having a length with two terminal ends and an intermediate portion, said handle having two co-extensive walls free of any curvature and said walls defining a slot between said walls and said intermediate portion of said spring being movably confined in said slot against movement toward and away relative to said pawls, and said two terminal ends extending from said intermediate portion and into contact with respective ones of said pawls for urging said pawls into engagement with said gear. 13. The ratcheting tool as claimed in claim 12, wherein: there is a circle concentric to said axis and said slot extends tangentially relative to said circle. 14. The ratcheting tool as claimed in claim 13, wherein: said slot is disposed in said handle at a location equidistant from both said two pawls. 15. The ratcheting tool as claimed in claim 12, wherein: said spring has two leg portions extending from said intermediate portion to respective ones of said terminal ends, said handle has had two spaced-apart surfaces fixed thereon, and said spring two leg portions are disposed to respectively abut said handle surfaces and thereby place said spring under spring-bending tension to thereby enhance both the confinement of said spring in said slot and the urging of said spring into contact with said pawls. 16. A method of securing a spring in a ratcheting tool having a handle with an axis, a gear, and two pawls movably engagable with said gear, the improvement comprising the steps of: forming an elongated pocket in said handle and spaced from said axis and defined by two co-extensive and planar walls, forming a spring with a length having two terminal ends and an intermediate portion between said ends, said pocket and said intermediate portion having a similar shape and with said intermediate portion snugly disposed in said pocket to be anchored relative to said handle, and positioning said spring two terminal ends in respective contact with said two pawls for urging said pawls into engagement with said gear. 17. The method of securing a spring as claimed in claim 16, including the steps of: forming said spring in a shape to thereby have a leg extending between said intermediate portion and each of said terminal ends, and forming two surfaces on said handle and positioning each said leg in abutment with a respective one of said surfaces for enhancing both the anchoring and the spring tension of said spring. 18. The method of securing a spring as claimed in claim 16, including the steps of: having said spring in a shape having two legs extending from said intermediate portion, and placing a bend in each of said two legs in a direction to enhance the spring force transmitted by said spring on said pawls. 19. The method of securing a spring as claimed in claim 16, including the step of: presenting said pocket in the shape of a narrow and elongated slit in said handle. 20. The method of securing a spring as claimed in claim 16, including the step of: placing said spring onto said handle by bending said two legs and thereby place a spring stress in said spring and maintaining that stress in said spring in the assembled position with said handle. id coupling, comprising: a drive shaft adapted for connection to a rotation shaft of an engine; a housing rotatably supported to the drive shaft; a predetermined amount of viscous fluid disposed in the housing; an operation plate set in the housing and dividing a space defined within the housing into a viscous fluid reservoir and an operation chamber into which the viscous fluid can be introduced from the reservoir, the operation plate comprising a communication hole communicating the reservoir and the operation chamber to permit viscous fluid to transfer between the reservoir and the operation chamber; a rotor disposed in the operation chamber and fixed to the drive shaft; a valve mechanism opening and closing the communication hole according to a temperature of the housing to control a flow of a viscous fluid from the viscous fluid reservoir to the operation chamber; and a torque transmitting section comprising a plurality of first circumferential projections concentrically formed on a portion of the housing and a plurality of second circumferential projections concentrically formed on an outer peripheral portion of the rotor, the first circumferential projections being spacedly interleaved with the second circumferential projections and adapted to be fluidly coupled with each other through the viscous fluid, an axial dimension of a radially inner projection of the circumferential projections of at least one of the housing and the rotor being greater than an axial dimension of a radially outer projection of the circumferential projections of the at least one of the housing and the rotor, and wherein the housing is dimensioned such that when the engine is stopped and the housing is stationary, the predetermined amount of viscous fluid in the operating chamber is such that a radially outermost circumferential projection on the housing portion and a radially outermost circumferential projection on the rotor are dipped in the viscous fluid. 4. A viscous fluid coupling, comprising: a drive shaft adapted for connection to a rotation shaft of an engine; a housing rotatably supported to the drive shaft, a predetermined amount of viscous fluid being disposed in the housing; an operation plate set in the housing and dividing a space defined within the housing into a viscous fluid reservoir and an operation chamber, the operation plate comprising a communication hole communicating viscous fluid between the reservoir and the operation chamber; a rotor disposed in the operation chamber and fixed to the drive shaft; a valve mechanism opening and closing the communication hole according to a temperature of the housing to control flow of the viscous fluid from the viscous fluid reservoir to the operation chamber; and a torque transmitting section comprising a plurality of first circumferential projections concentrically formed on the housing and a plurality of second circumferential projections concentrically formed on the rotor; wherein: the first circumferential projections are interleaved with the second circumferential projections so as to overlap therewith and are adapted to be fluidly coupled with each other through the viscous fluid, an axial dimension of a radially inner projection of the circumferential projections in a direction parallel to an axis about which the rotor is rotatable, on one of the housing and the rotor, is greater than an axial dimension of a radially outer projection in a direction parallel to an axis about which the rotor is rotatable, of the circumferential projections of the other of the housing and the rotor, the circumferential projections of the other of the housing and the rotor having the same axial dimension, and wherein the housing is dimensioned such that when the housing is stationary, a level of the predetermined amount of viscous fluid in the operating chamber is such that of a radially outermost circumferential projection on the housing and a radially outermost circumfe