Telescopic slide rail support pulley structure

A telescopic slide rail support pulley structure, comprising:

• a first rail comprising a plurality of mounting holes and at least one first rolling carriage;
• a second rail comprising a notch and at least one positioning hole and at least one second rolling carriage, said second rail being movably mounted on said first rail;
• a support pulley assembly comprising at least one upper roller, at least one lower roller, a support holder, a support piece, a connecting portion, an upper roller groove and a lower roller groove, said at least one upper roller being arranged to said upper roller groove, said at least one lower roller being arranged to said lower roller groove, said support piece being arranged on one side of said support holder, said connecting portion being connected to one end of said support holder mounted to said notch of said second rail;
• a third rail movably mounted on said second rail, and wherein at least one second rolling carriage is arranged between the second rail and the third rail;
• wherein said at least one first rolling carriage is arranged between said first rail and said second rail;
• and
• wherein said support pulley assembly further comprises an elastic arm and a positioning protrusion, said positioning protrusion being connected to said elastic arm, said elastic arm being connected to one end of said support holder.