Disclosed is a hoist mechanism comprising a lifting arm wherein: when the lifting arm is in a fully raised position, a projecting upper end section of a major part of the lifting arm extends substantially horizontally an effective length of the projecting upper end section is made variable by the provision of an extension element adjustably fixed to it and the lifting arm is variable in upstanding height by a provision of a lower end section slidably connected to the major part of the lifting arm, wherein both length and height variations are made by stepless adjustments.
