AU2144888A - Pallets - Google Patents

Pallets

Info

Publication number
AU2144888A
AU2144888A AU21448/88A AU2144888A AU2144888A AU 2144888 A AU2144888 A AU 2144888A AU 21448/88 A AU21448/88 A AU 21448/88A AU 2144888 A AU2144888 A AU 2144888A AU 2144888 A AU2144888 A AU 2144888A
Authority
AU
Australia
Prior art keywords
pallets
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
AU21448/88A
Inventor
Wilhelm Andreas Cool
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of AU2144888A publication Critical patent/AU2144888A/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D19/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D19/0004Rigid pallets without side walls
    • B65D19/0006Rigid pallets without side walls the load supporting surface being made of a single element
    • B65D19/0008Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface
    • B65D19/001Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface the base surface being made of a single element
    • B65D19/0012Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface the base surface being made of a single element forming a continuous plane contact surface
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D19/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D19/0004Rigid pallets without side walls
    • B65D19/0006Rigid pallets without side walls the load supporting surface being made of a single element
    • B65D19/0008Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface
    • B65D19/001Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface the base surface being made of a single element
    • B65D19/0014Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface the base surface being made of a single element forming discontinuous or non-planar contact surfaces
    • B65D19/0018Rigid pallets without side walls the load supporting surface being made of a single element forming a continuous plane contact surface the base surface being made of a single element forming discontinuous or non-planar contact surfaces and each contact surface having a discrete foot-like shape
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D19/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D19/0004Rigid pallets without side walls
    • B65D19/0053Rigid pallets without side walls the load supporting surface being made of more than one element
    • B65D19/0055Rigid pallets without side walls the load supporting surface being made of more than one element forming a continuous plane contact surface
    • B65D19/0057Rigid pallets without side walls the load supporting surface being made of more than one element forming a continuous plane contact surface the base surface being made of a single element
    • B65D19/0059Rigid pallets without side walls the load supporting surface being made of more than one element forming a continuous plane contact surface the base surface being made of a single element forming a continuous plane contact surface
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00009Materials
    • B65D2519/00014Materials for the load supporting surface
    • B65D2519/00034Plastic
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00009Materials
    • B65D2519/00049Materials for the base surface
    • B65D2519/00069Plastic
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00263Overall construction of the pallet
    • B65D2519/00268Overall construction of the pallet made of one piece
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00263Overall construction of the pallet
    • B65D2519/00273Overall construction of the pallet made of more than one piece
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00263Overall construction of the pallet
    • B65D2519/00278Overall construction of the pallet the load supporting surface and the base surface being identical
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00283Overall construction of the load supporting surface
    • B65D2519/00288Overall construction of the load supporting surface made of one piece
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00283Overall construction of the load supporting surface
    • B65D2519/00308Overall construction of the load supporting surface grid type, e.g. perforated plate
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00313Overall construction of the base surface
    • B65D2519/00318Overall construction of the base surface made of one piece
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00313Overall construction of the base surface
    • B65D2519/00328Overall construction of the base surface shape of the contact surface of the base
    • B65D2519/00333Overall construction of the base surface shape of the contact surface of the base contact surface having a stringer-like shape
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00258Overall construction
    • B65D2519/00313Overall construction of the base surface
    • B65D2519/00363Overall construction of the base surface grid type, e.g. perforated plate
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00547Connections
    • B65D2519/00552Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer
    • B65D2519/00557Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer without separate auxiliary elements
    • B65D2519/00562Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer without separate auxiliary elements chemical connection, e.g. glued, welded, sealed
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00547Connections
    • B65D2519/00552Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer
    • B65D2519/00557Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer without separate auxiliary elements
    • B65D2519/00567Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer without separate auxiliary elements mechanical connection, e.g. snap-fitted
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00547Connections
    • B65D2519/00552Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer
    • B65D2519/00572Structures connecting the constitutive elements of the pallet to each other, i.e. load supporting surface, base surface and/or separate spacer with separate auxiliary element, e.g. screws, nails, bayonets
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00736Details
    • B65D2519/00825Finishing of the external surfaces
    • B65D2519/0083Anti-slip means
    • B65D2519/0084Separated elements, e.g. including in-moulded elements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2519/00Pallets or like platforms, with or without side walls, for supporting loads to be lifted or lowered
    • B65D2519/00004Details relating to pallets
    • B65D2519/00736Details
    • B65D2519/00935Details with special means for nesting or stacking
    • B65D2519/0094Details with special means for nesting or stacking nestable

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Pallets (AREA)
AU21448/88A 1987-08-26 1988-08-24 Pallets Abandoned AU2144888A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA876360 1987-08-26
ZA87/6360 1987-08-26

Publications (1)

Publication Number Publication Date
AU2144888A true AU2144888A (en) 1989-03-02

Family

ID=25578967

Family Applications (1)

Application Number Title Priority Date Filing Date
AU21448/88A Abandoned AU2144888A (en) 1987-08-26 1988-08-24 Pallets

Country Status (4)

Country Link
EP (1) EP0305082A1 (en)
AU (1) AU2144888A (en)
IL (1) IL87401A0 (en)
PT (1) PT88337A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995032901A1 (en) * 1994-06-01 1995-12-07 Peter John Warneford Pallet made from plastic flute board
WO1996003322A1 (en) * 1994-07-22 1996-02-08 Pallenz Limited Two-piece moulded plastic pallet

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2105118T3 (en) * 1992-11-13 1997-10-16 Cadillac Products PLASTIC MATTER PLATFORM.
GB0301555D0 (en) * 2003-01-23 2003-02-26 D W Plastics Nv A pallet provided with friction elements
GB2411638A (en) * 2004-03-06 2005-09-07 Boydell & Jacks Ltd A stackable pallet
AU2005223472B2 (en) * 2004-03-19 2011-10-27 Pvaxx Research And Development Limited Load-carrying apparatus and methods of manufacture
GB2413331B (en) * 2004-03-19 2008-10-29 Pvaxx Res & Dev Ltd Load-carrying apparatus and methods of manufacture
GB2425506B (en) 2005-04-26 2010-11-10 Pvaxx Res & Dev Ltd Load carrying apparatus and method of manufacture
WO2007123421A1 (en) * 2006-04-24 2007-11-01 Algen Holdings Limited Plastic pallet platform and base with mating sets of posts
WO2008054219A1 (en) * 2006-10-30 2008-05-08 Euro Composite Plastic As Pallet for reuse, made of plastic
CN102712389B (en) * 2009-10-13 2016-08-03 斯帕索斯塑料两合公司 Pallet foot, pallet and with the chest of leg and for adhering to the pallet foot method to platform
WO2015004601A1 (en) * 2013-07-10 2015-01-15 Karl-Heinz Schmitt Pallets
GB2530237B (en) * 2014-06-04 2021-09-22 Gridesic Holdings Ltd Structural element
GB2530810A (en) * 2014-10-03 2016-04-06 Stewart Ronald Green Profile pallets

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3680496A (en) * 1970-06-08 1972-08-01 Edward B Westlake Jr Plastic pallet
US4604014A (en) * 1984-07-12 1986-08-05 Illinois Tool Works Inc. Pallet fastener

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995032901A1 (en) * 1994-06-01 1995-12-07 Peter John Warneford Pallet made from plastic flute board
WO1996003322A1 (en) * 1994-07-22 1996-02-08 Pallenz Limited Two-piece moulded plastic pallet

Also Published As

Publication number Publication date
IL87401A0 (en) 1989-01-31
EP0305082A1 (en) 1989-03-01
PT88337A (en) 1989-06-30

Similar Documents

Publication Publication Date Title
AU2583688A (en) Pallet
AU6548986A (en) Pallet construction
AU614965B2 (en) Thiadiazinones
AU2611588A (en) New phenylethanolamines
AU1407388A (en) Substituted di-t-butylphenols
AU2222388A (en) Peptidylheterocycles
AU1381888A (en) Timeswitches
AU1301788A (en) Chemo-radio-immuno-conjugates
AU5241890A (en) Pallets
AU2142288A (en) New aluminium-magnesium-hydroxy-compounds
AU581460B2 (en) Pallet
AU2144888A (en) Pallets
AU1764488A (en) Substituted 5-methylamino-1-arylpyrazoles
AU1210388A (en) Novel aminohydrocarbyl-substituted ketoximosilanes
AU2665388A (en) 17-methylene-and 17-ethylidene-estratrienes
AU1590788A (en) Leukaemia-inhibitory factor
AU1158888A (en) Scraper-spreader
AU1366388A (en) Videosystem
AU2021888A (en) Sulphonylaminoguanidinoazines
AU2505988A (en) 3-aminopyrazolin-5-ones
AU2456688A (en) Dripulator
AU2698888A (en) Naphthothiazepinones
AU2183888A (en) Auto-ejector
AU1217388A (en) Heterocyclyl-2-propyn-1-amines
AU1325188A (en) 23-phenylsteroids