Tightener for a Belt Drive Operating in the Presence of Oil
A tightener ( 1 ) cooperating with a belt in the presence of oil, and having a pin ( 2 ) having a first axis (A); a base plate ( 15 ) integral with and substantially perpendicular to the pin ( 2 ); a cam arm ( 3 ) connected in rotary manner to the pin ( 2 ) and movable with respect to the base plate ( 15 ); a contact member ( 5 ) carried by the cam arm ( 3 ); and an elastic member ( 4 ) connected to the cam arm ( 3 ) to activate the contact member ( 5 ) against the belt. The tightener ( 1 ) also has a friction member ( 16 ) made of oil-resistant material and axially supporting the cam arm ( 3 ) on the base plate ( 15 ); and axial elastic means ( 24 ) for loading the friction member ( 16 ) against the base plate ( 15 ).
1 . A tightener for a belt drive operating in the presence of oil, comprising a pin having a first axis; a base plate integral with and substantially perpendicular to said pin; a cam arm connected in rotary manner to said pin and movable with respect to said base plate; a contact member carried by said arm; and an elastic member connected to said arm to activate said contact member against said belt; a friction member axially supporting said arm on said base plate; and axial elastic means for loading said friction member against said base plate; characterized in that said friction member is made of an oil-resistant polymer material and is radially interposed between said elastic member and said contact member.
2 . A tightener as claimed in claim 1 , characterized in that said arm defines a seat coaxial with said first axis; and in that said axial elastic means are housed inside said seat.
3 . A tightener as claimed in claim 2 , characterized by comprising a tightening plate connected rigidly to said pin to compress said axial elastic means.
4 . A tightener as claimed in claim 3 , characterized in that said tightening plate defines a gap to permit lubrication of said axial elastic means.
5 . A tightener as claimed in claim 1 , characterized in that said axial elastic means directly contact said arm.
6 . A tightener as claimed in claim 1 , characterized in that said contact member comprises a hollow pulley.
7 . A tightener as claimed in claim 1 , characterized in that said contact member comprises a shoe connected to said arm.
8 . A tightener as claimed in claim 1 , characterized in that said friction member comprises rock wool, magnesium oxide, graphite, and clay.
9 . A tightener as claimed in claim 8 , characterized in that said friction member comprises a caoutchouc-based binder.
10 . A tightener as claimed in claim 1 , characterized in that said arm defines a housing completely housing said elastic member.