Portable tennis ball testing device

A portable device for use in determining whether a tennis ball complies with a pre-established deformation standard, comprising:

• a frame including a plurality of support rods extending in parallel relationship with one another;
• a first plate and a second plate fixed to said support rods and disposed in spaced relationship to one another;
• a ball-compressing sliding component disposed between said first plate and said second plate, said ball-compressing sliding component including:
• a third plate and a fourth plate coupled to said support rods for mutually independent sliding motion along said support rods;
• and
• an elastic element or spring of predetermined height and a predetermined monotonic force vs. distance function F(x), said elastic element or spring being disposed between and in contact with said third plate and said fourth plate;
• means for moving said sliding component so as to compress both said elastic element or spring and a ball inserted between said second plate and one of said third plate and said fourth plate;
• means for limiting a compression distance of said elastic element or spring to d=F−1(f), where the force f=F(d) required to compress the spring the distance d has a predetermined value;
• and
• means mounted at least indirectly to said support rods for measuring a degree or deformation or compression of the ball,
• wherein said sliding component has a total weight w less than or equal to a specified preload p, with the preload increased to p by compressing said elastic element or spring a measured compression distance d1=F−1(p−w), so that the total preload becomes w+F(d1)=p.

A portable device for use in determining whether a tennis ball complies with a pre-established deformation standard, comprising:

• a frame including a plurality of support rods extending in parallel relationship with one another;
• a first plate and a second plate fixed to said support rods and disposed in spaced relationship to one another;
• a ball-compressing sliding component disposed between said first plate and said second plate, said ball-compressing sliding component including:
• a third plate and a fourth plate coupled to said support rods for mutually independent sliding motion along said support rods;
• and
• an elastic element or spring of predetermined height and a predetermined monotonic force vs. distance function F(x), said elastic element or spring being disposed between and in contact with said third plate and said fourth plate;
• means for moving said sliding component so as to compress both said elastic element or spring and a ball inserted between said second plate and one of said third plate and said fourth plate;
• means for limiting a compression distance of said elastic element or spring to d=F−1(f), where the force f=F(d) required to compress the spring the distance d has a predetermined value;
• and
• means mounted at least indirectly to said support rods for measuring a degree or deformation or compression of the ball,
• the means for measuring the deformation of the ball including a measuring rod movably traversing a hole in said fourth plate, said measuring rod being provided with a pointer in the form of an elongate arm or a disk attached to said measuring rod and extending in a plane perpendicular to an axis thereof.

A portable device for use in determining whether a tennis ball complies with a pre-established deformation standard, comprising:

• a frame including a plurality of support rods extending in parallel relationship with one another;
• a first plate and a second plate fixed to said support rods and disposed in spaced relationship to one another;
• a ball-compressing sliding component disposed between said first plate and said second plate, said ball-compressing sliding component including:
• a third plate and a fourth plate coupled to said support rods for mutually independent sliding motion along said support rods;
• and
• an elastic element or spring of predetermined height and a predetermined monotonic force vs. distance function F(x), said elastic element or spring being disposed between and in contact with said third plate and said fourth plate;
• means for moving said sliding component so as to compress both said elastic element or spring and a ball inserted between said second plate and one of said third plate and said fourth plate;
• means for limiting a compression distance of said elastic element or spring to d=F−1(f), where the force f=F(d) required to compress the spring the distance d has a predetermined value;
• and
• means mounted at least indirectly to said support rods for measuring a degree or deformation or compression of the ball,
• further comprising:
• a measuring rod attached to said third plate and extending towards said fourth plate for measuring a compression distance of said elastic element or spring, said measuring rod being provided at one end with a pointer;
• an elongate marker member attached to said fourth plate and extending toward said third plate, said elongate marker member being provided with a zero-distance mark, said pointer being aligned with said zero-distance mark prior to compression of said elastic element or spring, said elongate marker member being further provided with a distance d1 mark, so that a preload force takes on a predetermined initial value upon a compressing of said elastic element or spring the distance d1, as indicated by the pointer pointing to the distance d1 marker.

A method for determining whether a tennis ball is compliant with a predetermined deformation standard, comprising:

• providing a device including a frame, a rigid first plate member and a rigid second plate member, first plate member and said second plate member being disposed in substantially parallel relationship to one another and mounted to said frame so that said first plate member is movable alternately towards and away from said second plate member;
• inserting the tennis ball between said first plate member and said second plate member;
• upon inserting said tennis ball between said first plate member and said second plate member, moving said first plate member towards said second plate member to place said tennis ball under a predetermined preliminary load;
• shifting said first plate member further toward said second plate member to exert an additional force of predetermined magnitude on said tennis ball;
• and
• visually reading an indicator position relative to a scale element mounted to said frame, said indicator position providing an indication of an amount of deformation of said tennis ball,
• wherein the visual reading of said indicator position includes setting a pointer on a rod at a zero-distance mark on said scale element before said tennis ball is compressed, and reading a position of said pointer on said scale element after said tennis ball is compressed.