What is claimed is:
1. A tank cap apparatus, comprising:
a tank opening member having an opening engagement element and a sealing surface;
a cap constructed and arranged to close the tank opening member through rotation about a rotation axis, the cap including a cap engagement element for engaging the opening engagement element; and
a gasket interposed between the cap and the sealing surface of the tank opening member to seal a gap therebetween;
wherein the opening engagement element is inclined at a predetermined angle relative to a direction orthogonal to the rotation axis of the cap, the predetermined angle being an angle at which the gasket is compressed according to a closing operation of the cap; and
wherein the cap engagement element has a guide surface that engages with the opening engagement element by a rotation of the cap in a closing direction while the cap is inserted into the tank opening member, an angle of the guide surface for contacting with the opening engagement element being constructed and arranged to decrease with a rotation of the cap during the closing operation.
2. The tank cap apparatus in accordance with claim 1, wherein the guide surface has a first inclined surface and a second inclined surface inclined respectively at an angle of a direction orthogonal to the rotation axis of the cap, an angle of the first inclined surface being greater than the predetermined angle of the opening engagement element, an angle of the second inclined surface being substantially equal to the predetermined angle.
3. The tank cap apparatus in accordance with claim 2, wherein the gasket is a C-ring.
4. The tank cap apparatus in accordance with claim 1, wherein the tank cap apparatus is configured such that the cap engagement element is engaged with the opening engagement element by rotation of the cap by an angle of 180 or less.
5. The tank cap apparatus in accordance with claim 4, further comprising a tilt-preventing rib formed on an outer circumferential portion of the cap between the cap engagement element and the gasket, the tilt-preventing rib being constructed and arranged to come into contact with an inner wall of the tank opening member, thereby preventing the cap from tilting upon application of a cap-tilting force.
6. The tank cap apparatus in accordance with claim 5, wherein the tilt-preventing rib is disposed above an outer circumferential portion of the cap exclusive of the cap engagement element.
7. The tank cap apparatus in accordance with claim 6, wherein the tilt-preventing rib extends to a radial height substantially equal to or greater than a radial height of the cap engagement element.
8. A tank cap apparatus, comprising:
a tank opening member having an opening engagement element and a sealing surface;
a cap constructed and arranged to close the tank opening member through rotation about a rotation axis, the cap including a cap engagement element for engaging the opening engagement element; and
a gasket interposed between the cap and the sealing surface of the tank opening member to seal a gap therebetween;
wherein the opening engagement element is inclined at a predetermined angle relative to a direction orthogonal to the rotation axis of the cap, the predetermined angle being an angle at which the gasket is compressed according to a closing operation of the cap; and
wherein the cap engagement element has a guide surface that engages with the opening engagement element by a rotation of the cap in a closing direction while the cap is inserted into the tank opening member, an angle of the guide surface for contacting with the opening engagement element being constructed and arranged to be greater than the predetermined angle of the opening engagement element.
9. The tank cap apparatus in accordance with claim 8, wherein the gasket is a C-ring.
10. The tank cap apparatus in accordance with claim 8, wherein the tank cap apparatus is configured such that the cap engagement element is engaged with the opening engagement element by rotation of the cap by an angle of 180 or less.
11. The tank cap apparatus in accordance with claim 10, further comprising a tilt-preventing rib formed on an outer circumferential portion of the cap between the cap engagement element and the gasket, the tilt-preventing rib being constructed and arranged to come into contact with an inner wall of the tank opening member, thereby preventing the cap from tilting upon application of a cap-tilting force.
12. The tank cap apparatus in accordance with claim 11, wherein the tilt-preventing rib is disposed above an outer circumferential portion of the cap exclusive of the cap engagement element.
13. The tank cap apparatus in accordance with claim 12, wherein the tilt-preventing rib extends to a radial height substantially equal to or greater than a radial height of the cap engagement element.
14. A tank cap for closing a tank opening member provided with an opening engagement element formed in an inclined state at a predetermined angle, comprising:
a casing main body including (i) a flange formed in an upper portion the casing main body, (ii) a gasket holder disposed underneath the flange, and (iii) a cap engagement element formed underneath the gasket holder;
a gasket held by the gasket holder, the gasket sealing a gap around a sealing surface of the tank opening member; and
a cover rotatably mounted over the flange;
wherein the cap engagement element has a guide surface constructed and arranged to be engaged with the opening engagement element by a rotation of the cap in a closing direction while the tank cap is inserted into the tank opening member, an angle of the guide surface for contacting with the opening engagement element being constructed and arranged to decrease with a rotation of the cap during the closing operation.
15. The tank cap in accordance with claim 14, wherein the guide surface has a first inclined surface and a second inclined surface inclined respectively at an angle of a direction orthogonal to the rotation axis of the cap, an angle of the first inclined surface being greater than the predetermined angle of the opening engagement element, and an angle of the second inclined surface being substantially equal to the predetermined angle.
16. The tank cap in accordance with claim 14, wherein the tank cap is configured such that the cap engagement element is engaged with the opening engagement element by rotation of the cap by an angle of 180 or less.
17. The tank cap in accordance with claim 16, further comprising a tilt-preventing rib formed on an outer circumferential portion of the casing main body between the cap engagement element and the gasket, the tilt-preventing rib being constructed and arranged to come into contact with an inner wall of the tank opening member, thereby preventing the tank cap from tilting upon application of a cap-tilting force.
18. The tank cap in accordance with claim 17, wherein the tilt-preventing rib is disposed above an outer circumferential portion of the casing main body exclusive of the cap engagement element.
19. A tank cap for closing a tank opening member provided with an opening engagement element formed in an inclined state at a predetermined angle, comprising:
a casing main body including (i) a flange formed in an upper portion the casing main body, (ii) a gasket holder disposed underneath the flange, and (iii) a cap engagement element formed underneath the gasket holder;
a gasket held by the gasket holder, the gasket sealing a gap around a sealing surface of the tank opening member; and
a cover rotatably mounted over the flange;
wherein the cap engagement element has a guide surface constructed and arranged to be engaged with the opening engagement element by a rotation of the cap in a closing direction while the tank cap is inserted into the tank opening member, an angle of the guide surface for contacting with the opening engagement element being constructed and arranged to be greater than the predetermined angle of the opening engagement element.
20. The tank cap apparatus in accordance with claim 19, wherein the gasket is a C-ring.
21. The tank cap apparatus in accordance with claim 19, wherein the tank cap apparatus is configured such that the cap engagement element is engaged with the opening engagement element by rotation of the tank cap by an angle of 180 or less.
22. The tank cap apparatus in accordance with claim 21, further comprising a tilt-preventing rib formed on an outer circumferential portion of the casing main body between the cap engagement element and the gasket, the tilt-preventing rib being constructed and arranged to come into contact with an inner wall of the tank opening member, thereby preventing the tank cap from tilting upon application of a cap-tilting force.
23. The tank cap apparatus in accordance with claim 22, wherein the tilt-preventing rib is disposed above an outer circumferential portion of the casing main body exclusive of the cap engagement element.
24. The tank cap apparatus in accordance with claim 23, wherein the tilt-preventing rib extends to a radial height substantially equal to or greater than a radial height of the cap engagement element.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An escalator having a twin chain drive system, each chain comprising links consisting of two side plates interconnected by hollow sleeves on which are mounted load bearing rollers, said links being pivotally connected together to form a chain by linking plates and pins that are inserted through holes in the linking plates, and through the bores of the sleeves, characterised in that the hollow sleeves of pairs of selected sleeves spaced at intervals along the length of the chains, each have a bore that is provided with a double tapered surface that converges at a radial plane midway between the side plates of the respective link, and means for carrying a lateral constraint wheel, there being provided an axle comprising a spindle located in the tapered bores of the sleeves of each pair of sleeves of each chain, a spacer assembly located between the sleeves of each pair of sleeves, and means for clamping the chains and said spacer together axially thereby to hold the chains a predetermined distance apart, abutting surfaces of each sleeve of each pair of sleeves and the spacer assembly being of complementary curved shapes that permit relative movement between the spacer assembly and each sleeve of each pair of sleeves whilst maintaining the alignment of the axis of each sleeve of each pair of sleeves orthogonal to the sides of the links of the chain, there being further provided on one end of each axle a rotatable guide wheel that in use engages a guide rail adjacent only one side of one of the chains.
2. An escalator as claimed in claim 1, wherein a step or pallet of the escalator is attached to each axle.
3. An escalator as claimed in claim 1, wherein the guide wheel has a circumferential slot with opposing axially facing side walls that in operation engage the guide rail to provide lateral restraint.
4. An escalator as claimed in claim 3, wherein the guide rail has a cross sectional shape that is of a complementary shape to that of the slot.
5. An escalator as claimed in claim 3, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.
6. An escalator as claimed in claim 4, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.
7. An escalator as claimed in claim 2, wherein the guide wheel has a circumferential slot with opposing axially facing side walls that in operation engage the guide rail to provide lateral restraint.
8. An escalator as claimed in claim 7, wherein the guide rail has a cross sectional shape that is of a complementary shape to that of the slot.
9. An escalator as claimed in claim 8, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.
10. An escalator as claimed in claim 7, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.
11. An escalator as claimed in claim 2, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.
12. An escalator as claimed in claim 1, wherein the spacer assembly comprises a central tubular sleeve that has a fitting at each end that carries an insert and the insert is provided with a curved surface that co-operates with a curved surface on each sleeve of the pair of sleeves.