Engine Cooling System for a Skid-Steer Loader

A skid-steer vehicle is a compact, highly maneuverable vehicle which employs driving mechanisms on opposite sides of the vehicle for driving each set of wheels mounted thereon independently. The vehicle's maneuverability is further enhanced by a favorable weight ratio for the weight carried at the front and rear axles during loaded and unloaded conditions. It is desirable to provide as compact a vehicle structure as possible to maximize the efficiency of this weight ratio. In a skid-steer vehicle the engine is mounted in the rear and contributes significantly to a 70-30 weight ratio with 70% of the weight of the vehicle overlying the rear axle when the bucket at the front of the vehicle is unloaded. The conventional cooling system of prior art skid-steer vehicles stacks the cooling system in aligned relationship with the engine. That is, the fan, radiator and oil cooler are axially aligned behind the engine. This so-called "engine cooling stack" provides a relatively bulky cooling system.

Therefore, it would be desirable to shorten the length of this stack to provide a relatively compact and efficient cooling system for a skid-steer loader. A more compact cooling system provides a smaller engine compartment, permitting more efficient cooling of the engine and optimizes the weight ratio between the front and rear axles of the vehicles to improve the maneuvering ability of that vehicle.

Therefore, it is an object of the present invention to provide a compact cooling system for a skid-steer vehicle.

In a skid-steer vehicle embodying the present invention the engine is mounted conventionally in the rear of the vehicle and overlying the rear axle. A fan is mounted rearwardly of the axle, the fan reversely mounted to create negative pressure in the engine compartment. That is, the fan draws ambient air into the engine compartment through louvers provided in the rear portion of the engine compartment, carries the ambient air over the engine and pushes it out through a radiator mounted at an upper front portion of the compartment. An oil cooler is mounted beneath the radiator.

The cooling system of the present invention is substantially more compact than the conventional engine-fan-radiator-oil cooler stack of the prior art and, in fact, reduces the length of such stack by more than 20%. The compact structure of the present invention optimizes the efficiency of the cooling system and improves the maneuverability of the skid-steer vehicle due to the more favorable concentration of vehicle weight over the rear axle.

The present invention is embodied in the drawings provided herewith and such drawings should be considered with the detailed description provided below for a more complete understanding of the invention. The drawings may be described as follows:

FIG. 1 is a skid-steer vehicle employing the engine cooling system of the present invention;

FIG. 2 is a side elevational view of the cooling system of a skid-steer vehicle of the prior art; and

FIG. 3 is a side elevational view of the cooling system of the present invention.

A skid-steer vehicle 10 having a body portion 12 has mounted on opposite sides of the body portion rear uprights 14. The uprights 14 carry at an upper end portion thereof a boom assembly 16 pivotally mounted thereon and comprising opposite boom arms 18. The boom arms 18 extend outwardly at the front end of the vehicle to pivotally engage a bucket 20. Lift cylinders 22 control the boom arms 18 and a tilt cylinder (not shown) controls the bucket 20. Two sets of wheels 26 are provided on opposite sides of the vehicle 10. Each set of wheels 26 is controlled by an independent drive mechanism (not shown) controlled by its individual hand lever 28 provided on opposite sides of the driver's compartment 30. The skid-steer drive is operated by a hydrostatic drive system connected to the engine 32 of the vehicle 10. The drive system shall not be considered in detail but reference may be had to U.S. Pat. No. 3,635,635 and U.S. Pat. No. 3,866,700, assigned to the Assignee of the present invention, for a more complete description of a representative drive system for the vehicle of the present invention. The engine 32 is mounted in an engine compartment 34, defined by the uprights 14, a rear closure 35, a front panel 36 and an upper structure 37.

In the vehicle of the prior art an engine 32' is mounted in an engine compartment 34', defined by uprights 14', a rear closure 35', a front panel 36', and an upper structure 37'. The engine 32' is carried on a rear crossmember 33' underlying the body 12 of the skid-steer vehicle 10. Mounted rearwardly of the engine 32' is a fan 38, a radiator 39 and an oil cooler 40. The engine 32', the fan 38, the radiator 39 and the oil cooler 40 are mounted in stacked relation in the engine compartment to provide a relatively long disproportionate cooling system structure requiring a relatively large engine compartment with resultant cooling inefficiency.

The cooling system of the present invention employs an engine 32 comparable to the engine 32' of the prior art mounted in the engine compartment 34 on a rear crossmember 33 with a fan 42 mounted at the rear of the engine 32 in alignment therewith. A radiator 44 is mounted adjacent the upper structure 37 at a forward end of the engine compartment 34 overlying the engine 32. The radiator 44 is connected to the engine 32 by an L-shaped connection 48. An oil cooler 50 is mounted in the compartment 34 underlying the radiator 44. The rear closure 35 has louvers 54 provided therein to circulate ambient air through the engine. The fan 42 is mounted to provide negative pressure in the engine compartment. That is, the fan 42 draws ambient air into louvers 54 to carry ambient air over the engine and recirculate it out the top of the engine compartment 34 through the radiator 44.

The resultant cooling system concentrates the components of the system providing for a more compact engine structure, reduces the size of the cooling compartment and therefore substantially improves the efficiency of the cooling system. The compact structure of the cooling system of the present invention further concentrates the weight of the engine and its cooling system more closely to the rear axle of the vehicle, thereby to improve the maneuverability of the vehicle.

The present invention therefore provides a more compact, more efficient cooling system which indirectly contributes to the improved maneuverability of the vehicle.

Having thus described a preferred embodiment of the present invention it is recognized that modifications may be made in certain of the structure described without affecting the scope of the invention. The limits of the present invention are defined by the claims as set forth below.