A pedal (10) is formed from a single moulding and includes first and second arms (12, 14), each provided with an over moulded marker (16, 18). The pedal (10) has two fittings (20, 22) for coupling with a brake actuator rod (24) and a coupling member (26) respectively. A castor (40) includes a wheel (42) which can rotate about a bushing (44) and a coupling shaft (46). Within the shaft (46) there is provided a brake mechanism for locking the wheel (42). A base frame (80) for a bed includes longitudinal and transverse struts (52, 54) arranged in a rectangular form, with four castors (40) and four associated pedal assemblies (10). Two actuator rods (24) are provided, one for each pair of opposing pedal assemblies (10), while two connecting elements (26) are provided, one for each pair of side-by-side pedal assemblies (10). All the pedals and thus all the brake mechanisms are coupled to one another through the two actuator rods (24) and two coupling elements (26). When one pedal (10) is actuated all the castors will either be locked or will all be released by a single operation.