Speed adjustment device for a splatter arm in a garden sprinkler

The A speed adjustment device for control of the operation frequency of a splatter arm in a garden sprinkler, comprising:

• a sprinkler means having a rotatable main body, a pivotal splatter arm, a bias spring, a rotation angle limiting stop, a swivel control means and a pivot axis to which is secured the pivotal splatter arm;
• and
• an adjustment knob having a plurality of spaced stop protrusions disposed on the underside thereof;
• and a first peripheral groove adjacent to said stop protrusions being disposed on the underside of said adjustment knob for receiving the top of said bias spring;
• and a fixing groove being disposed inside of said first peripheral groove for securing one end of said bias spring;
• and a second peripheral groove being disposed on the top side of said adjustment knob for receiving an urging spring;
• said urging spring being in abutment against the top of said rotatable main body at one end and in abutment against said adjustment knob at the other end so as to urge said adjustment knob downward;
• a pair of stop members disposed right under said adjustment knob and being located on said rotatable main body so as to permit said plurality of spaced stop protrusions to be in selective engagement with said stop members, thereby said adjustment knob can be held in place with respect to the main body without turning;
• said splatter arm being connected to said bias spring and being able to be forced to pivot by the discharged water from said main body;
• said bias spring being connected to said adjustment knob at one end and to said splatter arm at the other end so that turning the adjustment knob can vary the tension of said bias spring and make the pivot span and operation frequency of said splatter arm changed accordingly.