Diagrammatic model in wood of Holt's patent 1876 Auxiliary Steam Reversing Gear

Diagrammatic model in wood of Holt's patent 1876 Auxiliary Steam Reversing Gear, on board

This auxiliary steam reversing gear was patented by Mr. Holt in 1876. The reversing piston has its motion controlled by a three-ported slide valve connected with the reversing lever, but also receiving motion from this piston. The ports of this valve are always open to the cylinder, but the passage of steam is prevented by a back cut-off valve of the ordinary type, without any lap. For each position of the control valve, which is moved by a hand lever, there is a corresponding neutral position for the three-ported valve, and therefore of the piston and reversing lever, so that any motion of the small valve is followed by a corresponding movement of the reversing piston until steam is again cut off from both ends of the cylinder.