A portable non-battery operated lamp has a spring wound up by hand for operation. The display comprises a first polarizer 5, a second polarizer 100 opposing the first polarizer 5, two twisted nematic liquid crystal layers 30, 60 between said first and second polarizers 5, 100 and a reflector 110 for reflecting light passing though the reflective region 122 of the display. The WTRU estimates a transmit power for each of a plurality of available TFCs and selects a TFC for each CCTrCH such that the sum of the estimated WTRU transmit power for selected TFCs is within a maximum WTRU transmit power. In addition, the second drive mechanism may include a safety catch configured to ensure the transmission of the vehicle remains in neutral as the mechanism propels the vehicle in forward or reverse direction at limited speeds.