A brake drum includes a generally cylindrical sidewall that is open at one end and at least partially closed by an endwall at its other end. The sidewall preferably has a thickness that vanes along its axial length and preferably is thickest at the end closest to the endwall. In one implementation, the outer surface of the sidewall is generally frustum shaped in cross section with a straight radially tapered outer wall. In another implementation, the outer surface of the sidewall is generally concave or sloped from the first end to a second end spaced from the endwall. In another implementation, the outer surface of the sidewall is generally convex.
1. A brake drum, comprising:
(a) an annular disk-shaped endwall adapted to be connected to a vehicle wheel for rotation about an axis, the endwall including a radially outermost portion,
(b) a sidewall extending generally parallel to the rotational axis having (1) an inner surface that extends from a first open end to a second end disposed toward the endwall with the inner surface defining a rub track section, and (2) a relatively smooth outer surface that is concave having a maximum cross sectional thickness disposed at or adjacent the second end and a minimum cross sectional thickness disposed a distance axially therefrom,
(c) a generally arcuate and concave transition portion extending from the endwall to the second end of the sidewall interconnecting the endwall and the sidewall, the transition portion connecting to an end surface of the second end of the sidewall, the end surface of the second end of the sidewall facing toward the endwall and defining a largest diameter portion of the brake drum, the transition portion further comprising a first portion that extends radially inward from the sidewall toward a remainder of the transition portion, the first portion having an outwardly facing surface that is coplanar with and continuously connects to the end surface of the second end of the sidewall, and
wherein the endwall, sidewall, and the transition portion define a brake drum formed in one unitary piece.
2. The brake drum of claim 1 wherein the first portion of the transition portion comprises an inner surface that juxtaposes a portion of an end of the rub track section, wherein the outwardly facing surface of the first portion faces toward the endwall, wherein the transition portion further includes an axially extending second portion connected to the endwall, and wherein the sidewall has a continuously variable thickness along its axial extent.
3. The brake drum of claim 1 wherein the entire outer surface of the sidewall is concave.
4. The brake drum of claim 1 wherein the portion of the sidewall having the maximum cross sectional thickness is between 1.2 and 7.5 times thicker than the portion of the sidewall having the minimum cross sectional thickness.
5. The brake drum of claim 1 wherein the portion of the sidewall having the maximum cross sectional thickness is between 2 to 4 times thicker than the portion of the sidewall having the minimum cross sectional thickness.
6. The brake drum of claim 1 wherein the thickness at the first open end of the sidewall has a cross sectional thickness of between 1.1 and 3.5 times the cross sectional thickness of the endwall.
7. A brake drum, comprising:
(a) an endwall adapted to be connected to a vehicle wheel for rotation about an axis, the endwall including a radially outermost portion,
(b) a sidewall extending generally parallel to the rotational axis having (1) an inner surface that extends from a first open end to a second end disposed toward the endwall with the inner surface defining a rub track section, and (2) a relatively smooth outer surface that is convex having a maximum cross sectional thickness disposed at or adjacent the second end and a minimum cross sectional thickness disposed a distance axially therefrom, and
(c) a radially and axially extending arcuate and concave transition portion connecting the endwall to an end surface defined at the second end of the sidewall and defining a largest diameter portion of the brake drum, the transition portion further comprising a first portion that extends radially inward from the sidewall toward a remainder of the transition portion, the first portion having an outwardly facing surface that is coplanar with and continuously connects to the end surface of the second end of the sidewall,
wherein the thickness of the sidewall varies along its axial extent such that the sidewall has a thickness in cross section that is greater adjacent to the transition portion than adjacent to the first open end, and
wherein the endwall, sidewall, and the transition portion define a brake drum formed in one unitary piece.
8. The brake drum of claim 7 wherein the transition portion comprises an axially extending second portion connected to the endwall and an interconnecting portion that interconnects the first portion and the second portion and which is disposed at an angle between the first portion and the second portion, and wherein the sidewall has a continuously variable thickness along its axial extent.
9. The brake drum of claim 7 wherein the portion of the sidewall having the maximum cross sectional thickness is between 1.2 and 7.5 times thicker than the portion of the sidewall having the minimum cross sectional thickness.
10. The brake drum of claim 7 wherein the thickness at the first open end of the sidewall has a cross sectional thickness of between 1.1 and 3.5 times the cross sectional thickness of the endwall.
11. A brake drum, comprising:
(a) an annular disk-shaped endwall adapted to be connected to a vehicle wheel for rotation about an axis,
(b) a sidewall extending generally parallel to the rotational axis having (1) an inner surface that extends from a first open end to a second end disposed toward the endwall with the inner surface comprising a rub track that is generally parallel to the rotational axis, and (2) a relatively smooth outer surface that is frustum shaped and linearly tapered from a maximum cross sectional thickness in a radial direction relative to the rotational axis disposed at or adjacent the second end to a minimum cross sectional thickness in the radial direction relative to the cross sectional thickness disposed at or adjacent the first open end,
(c) a radially and axially extending generally arcuate and concave transition portion connected to the endwall and connected to an end surface defined at the second end of the sidewall and defining a largest diameter portion of the brake drum at or adjacent the region of maximum thickness of the sidewall, the transition portion further comprising a first portion that extends radially inward from the sidewall toward a remainder of the transition portion, the first portion of the transition portion having an outwardly facing surface that is coplanar with and continuously connects to the end surface of the second end of the sidewall and
wherein the endwall, sidewall, and the transition portion define a brake drum formed in one unitary piece.
12. The brake drum of claim 11 wherein the transition portion has an axially extending second portion connected to the endwall, and an interconnecting portion extending at an angle between the first portion and the second portion.
13. The brake drum of claim 11 wherein the maximum cross sectional thickness of the sidewall is between 1.2 and 7.5 times thicker than the minimum cross sectional thickness of the sidewall.
14. The brake drum of claim 13 wherein the maximum cross sectional thickness of the sidewall is between 2 to 4 times thicker than the minimum cross sectional thickness of the sidewall.
15. The brake drum of claim 11 wherein the thickness of the sidewall at the first open end of the sidewall has a cross sectional thickness of between 1.1 and 3.5 times the cross sectional thickness of the endwall.
16. The brake drum of claim 1 wherein the first portion of the transition portion has opposing surfaces facing a portion of the rub track and toward the endwall, respectively, wherein the transition portion further comprises (1) an axially extending second portion connected to the endwall, and (2) an arcuate portion that interconnects the first portion and the second portion that (i) is disposed at an angle relative to the first portion, and (ii) is disposed at an angle relative to the second portion.
17. The brake drum of claim 16 wherein the arcuate portion of the transition portion has an inner surface that is generally arcuate.
18. The brake drum of claim 1 , wherein the first portion of the transition portion has an inwardly facing surface connecting to and extending orthogonally from the rub track section.
19. The brake drum of claim 1 , wherein the end surface of the second end of the sidewall is annular and intersects with an outer circumferential surface of the sidewall such that the annular end surface of the second end of the sidewall and the outer circumferential surface of the sidewall define an acute angle therebetween.