This invention relates to a cab heating system for a large construction vehicle, and more particularly, relates to a rotary fluid swivel that communicates heating fluid from a lower frame of the vehicle to a cab that is rotatable with respect to the frame.
Modern construction vehicles often have implements and cabs that can be rotated through 360 degrees with respect to the vehicle frame. This allows the implement and cab to face, and perform work, at any angular direction with respect to the position of the vehicle frame.
Typically vehicles utilize engine heat to heat the cab of the vehicle. An engine coolant fluid is passed over a hot engine and the coolant fluid is thus heated. The coolant fluid is then circulated, as a heating fluid, through a radiator in the cab which in turn warms the air within the cab.
Problems arise when this type of cab heating system is combined with a cab that is rotated with respect to the vehicle frame since fluid lines must pass from the vehicle frame and into the cab. If a fluid line is simply passed between the vehicle frame and the cab and fixed to each, the line will become twisted as the cab rotates with respect to the frame.
The prior art attempted to solve this problem by utilizing rotary fluid swivels for interconnecting the fluid lines from the vehicle frame to the cab. An example of a rotary fluid swivel is illustrated in U.S. Pat. No. 4,211,364 assigned to the assignee of the present invention, J. I. Case Company. The heating system disclosed in this patent is not the type which utilizes an engine coolant and a radiator, but instead utilizes a rotary fluid swivel connection to communicate heated air from the vehicle frame to the vehicle cab.
This prior art swivel allows leakage of the heated air. When using heated air as a heating fluid it is not important to prevent leakage of the heating fluid. However, leakage such as allowed by the above identified swivel would be quite undesirable when the heating fluid is a hot engine coolant, such as oil.
Another prior art device is illustrated in U.S. Pat. No. 4,352,456, also assigned to the assignee of the present invention, J. I. Case Company. As broadly shown in this patent, the vehicle cab is heated utilizing an engine coolant fluid that is passed over the engine. The heated coolant fluid leaves the hot engine and is passed through a radiator mounted within the vehicle cab.
The prior rotary fluid swivel was unsatisfactory for several reasons. It tended to leak the hot fluid that was used as a heating fluid. In addition, it tended to expand upon contact with the hot fluid to an extent that the expansion could sometimes cause increased friction between the rotary cab and the vehicle frame. In addition, the prior art rotary swivel had little bearing surface for the large rotating cab.
Several manufacturers of large construction vehicles have abandoned the idea of rotary fluid swivels. Some manufacturers mount the engine to rotate with the cab. This is undesirable since it requires complex connections between the frame and the engine.
Other manufacturers use a fuel burning heater in the cab. This is undesirable since it adds fuel cost. The heat from the engine is an available and inexpensive heat source that should preferably be utilized.
It is therefore, an object of the present invention to disclose a rotary fluid swivel to connect fluid lines from the frame of a vehicle to the cab of the vehicle that will prevent leakage of the fluid.
It is further an object of the present invention to disclose a rotary fluid swivel that will avoid undue expansion of the swivel members.
Moreover, it is an object of the present invention to create a rotary fluid swivel that embodies the above-noted objects and at the same time will withstand the large stresses and strains that will be placed upon it by the large rotating members.