Ratchet tensioner with plunger releasing mechanism

A ratchet tensioner comprising:

• a housing having a recessed groove;
• a plunger having an axis reciprocally mounted in the housing with one end of the plunger projecting outward from the housing said plunger having a series of rack teeth formed on an outer circumferential surface along the axis thereof;
• a plunger spring acting between the housing and the plunger and urging the plunger in a direction to project outward from the housing,
• a ratchet pawl and a pivot shaft pivotally mounting the pawl to the housing within said recessed groove formed in the housing, the ratchet pawl having a locking prong at one end thereof located on one side of the pivot shaft;
• a ratchet spring urging the ratchet pawl to turn about the axis of the pivot shaft in one direction so that the locking prong of the ratchet pawl is held in mesh with one of said series of rack teeth;
• and
• a plunger releasing mechanism for turning the ratchet pawl about the axis of the ratchet shaft in the opposite direction against the force of the plunger spring to disengage the locking prong of the ratchet pawl from the rack tooth of the plunger, the plunger releasing mechanism having
• a pin having a tip end,
• a pin insertion hole formed in the housing transversely across the recessed groove for permitting insertion of the pin from the exterior of the housing, the pin insertion hole being located a given distance from said pivot shaft on the opposite side of the pivot shaft from the locking prong, and
• a sloped surface formed on the ratchet pawl and normally extending obliquely across the axis of the pin insertion hole, the sloped surface, upon abutment with said tip end of the pin which is inserted in the pin insertion hole, being capable of causing the ratchet pawl to turn in said opposite direction against the force of the ratchet spring to thereby disengage the locking prong of the ratchet pawl from the rack tooth of the plunger for releasing the plunger.