A wheel braking mechanism 10 comprising a brake shaft 14, a brake drum 16, an engagement pedal 18 and a disengagement pedal 20. The brake shaft 14 has a plurality of first splines 22 provided around the brake shaft 14. A first alignment member 24 is provided at the end of each first spline 22 and has first and second oppositely directed chamfered alignment surface 24a, 24b. The brake drum 16 defines a brake socket around which are provided a plurality of second splines 28, which define a plurality of spline recesses 30. A second alignment member 31 is provided at the opposing end of each second spline 28. Movement of the brake shaft 14 towards the brake drum 16 causes the first alignment members 24 to travel down the respective alignment surfaces of the second alignment members 31, thereby aligning the first splines with the respective adjacent spline recess 30.