A piston-slipper assembly for use in a hydraulic apparatus having a plate operably associated with a slipper, the piston-slipper assembly comprising: a first member having a ball portion and an axially extending neck portion, and a second member having a socket having a circumferential extent greater than 180-degrees for receiving and retaining the ball portion in the socket while allowing swivelling movement of the ball portion, in which the socket opens to an end face of the second member at an opening which has a diameter less than a ball diameter of the ball portion for retaining the ball portion in the socket, characterised in that: the ball portion has reliefs provided at diametrically opposed sides of the ball portion that are aligned along a ball diameter of the ball portion perpendicular to an axis of the axially extending neck portion of the first member, the reliefs defining a reduced diameter portion of the ball portion having a relief width disposed through the centre of the ball portion that is less than the ball diameter of the ball portion for allowing passage of the ball portion into the socket, and the second member has a slot in a sidewall, in which, in a first orientation of the first member relative to the second member in which the axially extending neck portion is aligned with the slot and the reduced diameter portion is aligned with the opening, the neck portion can be moved into the slot and the ball portion can be moved through the opening, and in which passage of the ball portion through the opening is precluded in a second orientation of the first member relative to the second member in which the axially extending neck portion is not aligned with the slot. a first member having a ball portion and an axially extending neck portion, and a second member having a socket having a circumferential extent greater than 180-degrees for receiving and retaining the ball portion in the socket while allowing swivelling movement of the ball portion, in which the socket opens to an end face of the second member at an opening which has a diameter less than a ball diameter of the ball portion for retaining the ball portion in the socket, characterised in that: the ball portion has reliefs provided at diametrically opposed sides of the ball portion that are aligned along a ball diameter of the ball portion perpendicular to an axis of the axially extending neck portion of the first member, the reliefs defining a reduced diameter portion of the ball portion having a relief width disposed through the centre of the ball portion that is less than the ball diameter of the ball portion for allowing passage of the ball portion into the socket, and the second member has a slot in a sidewall, in which, in a first orientation of the first member relative to the second member in which the axially extending neck portion is aligned with the slot and the reduced diameter portion is aligned with the opening, the neck portion can be moved into the slot and the ball portion can be moved through the opening, the ball portion has reliefs provided at diametrically opposed sides of the ball portion that are aligned along a ball diameter of the ball portion perpendicular to an axis of the axially extending neck portion of the first member, the reliefs defining a reduced diameter portion of the ball portion having a relief width disposed through the centre of the ball portion that is less than the ball diameter of the ball portion for allowing passage of the ball portion into the socket, and the second member has a slot in a sidewall, in which, in a first orientation of the first member relative to the second member in which the axially extending neck portion is aligned with the slot and the reduced diameter portion is aligned with the opening, the neck portion can be moved into the slot and the ball portion can be moved through the opening, and in which passage of the ball portion through the opening is precluded in a second orientation of the first member relative to the second member in which the axially extending neck portion is not aligned with the slot.