Endless drive arrangement and tensioning system for same

A tensioner for tensioning a belt in an engine, comprising:

• a base that is mountable to a stationary member;
• a first tensioner arm that is pivotably connected to the base, wherein the first tensioner arm is biased in a first pivot direction for the first tensioner arm;
• a first bumper held in a first bumper receptacle on one of the base and the first tensioner arm, and a first travel limiter on the other of the base and the first tensioner arm;
• and
• a first pulley rotatably mounted to the first tensioner arm and positioned to engage a first section of the belt,
• wherein the first bumper has a proximal portion that is captured in the first bumper receptacle, a distal portion on which there is a distal face that is engageable with the first travel limiter to limit travel of the first tensioner arm in a second pivot direction for the first tensioner arm, wherein the first bumper has a longitudinal axis extending from the proximal portion to the distal face, and
• wherein the distal portion is spaced laterally from a side wall of the first bumper receptacle by a gap sized to limit lateral growth of the first bumper during compression of the first bumper,
• and wherein the gap increases in size in a distal direction.

A method for reducing peak hubloads in an endless drive arrangement for an engine, including a belt, a crankshaft that is driven by the engine to drive the belt, at least one accessory that is driven by the belt, and a tensioner including a base, a first tensioner arm that is movable relative to the base, a first pulley rotatably mounted on the tensioner arm and a tensioner biasing member that biases the first tensioner arm in a first free arm direction, the method comprising:

• a) providing a first bumper on one of the base and the first tensioner arm;
• b) providing a first travel limiter on the other of the base and the first tensioner arm;
• and
• c) moving the first tensioner arm relative to the base in a direction opposite to the first free arm direction, such that the bumper and the travel limiter engage one another,
• wherein the first bumper and the first travel limiter together have a selected first combined spring rate during engagement with one another, wherein the first combined spring rate increases progressively with compression between the first bumper and the first travel limiter.