biased to protrude from a housing by a spring a pair of wedge shaped cams are received in tapered recesses in the end of the housing cooperate with racks formed on opposite sides of the plunger and are urged against oblique seats formed by the tapered recesses by a biasing spring the cams and racks produce a ratcheting action maintaining chain tension by preventing retracting movement of the plunger the cams and racks disperse the load imparted to the plunger by the chain and reduce localized wear allowing the housing to be made from a light weight material such as aluminum accuracy requirements associated with conventional pawl type ratcheting tensioners are avoided application_number US 38791203 A description the chain tensioner 100 of the first embodiment illustrated in fig1 5 is an u201c outer attachment u201d type chain tensioner which is attached from the outside of an engine the tensioner is used to suppress the vibration generated as a timing chain tc travels over a crankshaft sprocket s 1 and camshaft sprockets s 2 of an engine and also to maintain proper tension in the chain in the chain tensioner 100 a spring biased cylindrical plunger 120 protrudes toward the timing chain tc which travels past a tensioner housing 110 attached to a wall e of the engine block wall the tensioner plunger presses against the back surface of a tensioner lever tl which is pivoted on the engine block so that a shoe surface.