Ratchet tensioner with backlash

A ratchet tensioner with a backlash, comprising:

• a housing having a plunger-accommodating hole formed therein;
• a plunger slidably received in the plunger-accommodating hole with one end portion projecting outward from the housing;
• a plunger spring acting between the housing and the plunger and urging the plunger in a first direction to project from the housing;
• rack teeth formed on an outer circumferential surface of the plunger along the axis of the plunger;
• a ratchet pawl pivotally mounted to the housing, the ratchet pawl having a first prong adapted to mesh with one of the rack teeth to prevent the plunger from moving in a second direction opposite to the first direction, and a second prong spaced a predetermined distance from the first prong in the second direction and engageable with a second tooth of the rack teeth to release meshing engagement between the first prong and the rack teeth when the plunger moves in the first direction;
• and
• a ratchet spring acting between the housing and the ratchet pawl and urging the ratchet pawl to turn in a direction to keep the meshing engagement between the first prong and the rack teeth, wherein
• the rack teeth each have a first flank facing toward the first direction and a second flank facing toward the second direction, the first flank being inclined at a first rack angle relative to a line perpendicular to the axis of the plunger on the bottom of a tooth space defined between each pair of adjacent rack teeth, the second flank being inclined at a second rack angle relative to the line perpendicular to the axis of the plunger on the bottom of the tooth space, the second rack angle being larger than the first rack angle.