Pet ramp system

A pet ramp system comprising:

• a first ramp having a near end, a far end of the first ramp spaced from the near end of the first ramp by a length in an a direction, the first ramp having only a single axle disposed at the near end of the first ramp and aligned with a b direction at ninety degrees to the a direction, the axle having a first radius, the first ramp having a tread panel aligned with an ab plane, a first rail of the first ramp disposed on a first side of the first ramp and extending along the first side from the near end in the a direction, a second rail of the first ramp disposed on a second side of the first ramp and extending along the first side from the near end in the a direction, the first rail and the second rail being thicker in a c direction than the tread panel, the c direction being at right angles to the a and b directions, the first rail spaced from the second rail by the tread panel, the first rail having a first thickness in the b direction, the second rail having a second thickness in the b direction;
• the first rail terminating at the near end of the first ramp in a first curved flange having a second radius that is greater than the first radius, the second rail terminating at the near end of the first ramp in a second curved flange having the second radius, the first curved flange having a first inboard-facing surface and the second curved flange having a second inboard-facing surface, the first inboard-facing surface spaced from the second inboard-facing surface in a −b direction opposite to the b direction by a first width;
• a pier having a base and a top elevated above the base, the base having a perimeter, the pier having a length in an x direction and a width in a y direction at right angles to the x direction, a first axle receiver of the pier disposed near the top of the pier and adapted to receive the axle of the first ramp, a second axle receiver of the pier disposed near the top of the pier and adapted to receive the axle of the first ramp, the first axle receiver being inwardly displaced in a −y direction opposite to the y direction from the perimeter of the base, the second axle receiver being inwardly displaced in the y direction from the perimeter of the base, the first and second axle receivers being disposed around a first axle receiver axis aligned with the y direction;
• the first axle receiver having a first outboard-facing surface conforming to a first xz plane, where z is a direction at right angles to the x and y directions, the second axle receiver having a second outboard-facing surface conforming to a second xz plane, the first xz plane spaced from the second xz plane in the y direction by a second width greater than the first width;
• the first axle receiver being positioned near a first side wall of the pier, the first side wall aligned with the x direction, the first side wall upwardly extending from the base of the pier to the top of the pier, the second axle receiver being positioned near a second side wall of the pier, the second side wall aligned with the x direction and spaced from the first side wall in the −y direction, the second side wall upwardly extending from the base of the pier to the top of the pier;
• a first rail flange pocket disposed outboard of the first axle receiver and formed in part by the first outboard-facing surface, a first concavely curved surface of the first rail flange pocket extending in the y direction from the first outboard-facing surface to the first side wall of the pier, a radius from any point on the first concavely curved surface to the first axle receiver axis being greater than the second radius, a depth of the first concavely curved surface in the y direction being greater than the first thickness of the first rail, a second rail flange pocket disposed outboard of the second axle receiver and formed in part by the second outboard-facing surface, a second concavely curved surface of the second rail flange pocket extending in the −y direction from the second outboard-facing surface to the second side wall of the pier, a depth of the second concavely curved surface in the y direction being greater than the second thickness of the second rail, a radius from any point on the second concavely curved surface to the first axle receiver axis being greater than the second radius, such that
• when the first and second axle receivers of the pier receive the axle of the first ramp, the axle of the first ramp will be positioned on the first axle receiver axis, the first rail flange will be received in the first rail flange pocket, and the second rail flange will be received in the second rail flange pocket, the first ramp then being capable of being articulated around the first axle receiver axis to any of a plurality of angular positions without interference from the first or second side walls of the pier.