| 摘要 |
<p>PCT No. PCT/GB89/00970 Sec. 371 Date Feb. 19, 1991 Sec. 102(e) Date Feb. 19, 1991 PCT Filed Aug. 21, 1989 PCT Pub. No. WO90/02241 PCT Pub. Date Mar. 8, 1990.A roller device (7) for equipment such as a ladder (5) has a rigid core (14) with an axle (17), and a surrounding more compressible rubber portion (8,9) circumferentially spaced portions of which are more readily compressible than adjacent portions so that the device will roll easily when not under load, but less easily when under load.</p> |
