Hydraulicspneumatics Com Sites Hydraulicspneumatics com Files Uploads Custom Inline Archive Www hydraulicspneumatics com Content Site200 Articles08 01 2006 24691 Ideas Appl0 00000013924

New Cat tool carrier follows the trends

Aug. 10, 2006
As with most mobile equipment, Caterpillar's IT38G tool carrier uses hydraulics for multiple functions of its operation. However, it also incorporates a variable-speed, loadsensing hydraulic fan drive, which helps conserve ...

Caterpillar's new IT38G tool carrier,looks like an articulated wheel loader. However, it's designed to use any of several general-purpose or specialized tools. So using it simply as a wheel loader would be like using your microwave oven to reheat your coffee — it does a great job, but it's capable of so much more.

As with most mobile equipment, Caterpillar's IT38G tool carrier uses hydraulics for multiple functions of its operation. However, it also incorporates a variable-speed, loadsensing hydraulic fan drive, which helps conserve fuel and reduce engine emissions.

John Baus, lead engineer for medium wheel loaders at Caterpillar, Peoria, Ill., explains that the IT38G has articulated steering, which makes it easy to maneuver, especially in tight spots. Baus says steering is accomplished with a two-piece chassis that pivots under the operator cabin. When the operator turns the steering wheel, say, to the right, a cylinder on the left side of the chassis extends, while an identical cylinder on the right side retracts.

Turning the steering wheel drives a gerotor-type pump, which directs hydraulic fluid in a pilot circuit to a proportional directional valve. This valve, in combination with other components, routes the correct flow of hydraulic fluid to and from the appropriate cylinders. Load sensing designed into the steering circuit directs power through the steering system only when needed. When steering is not needed, more power from the engine is available for implements.

Hydraulic fan drive
A trend in mobile equipment — especially large equipment — is the use of hydraulic fan drives to conserve energy and reduce emissions. Performance of diesel engines is very sensitive to operating temperature. An engine exhibits it highest power output per unit of fuel consumption within a relatively narrow range of temperatures. Likewise, a diesel engine produces the lowest amount of emissions per unit of power also within a relatively narrow temperature range. These two temperature ranges are not identical, but they generally overlap. Therefore, operating the engine within this overlapping temperature range produces maximum fuel economy and minimum emissions.

To keep an engine operating within this range, the cooling system maintains a relatively constant engine temperature even though engine speed, load, ambient temperature, and other factors are changing. The IT38G uses a variable-speed hydraulic fan drive to do just that.

The fan drive is powered by a variable-displacement axial-piston pump with load sensing. The load sensing feature minimizes power consumption of the fan drive when cooling demands are low — for example, when the equipment is operating in cold weather. From the pump, pressurized fluid flows through control valves to a fixeddisplacement gear motor, which drives the fan.

The large fan in this machine acts as a flywheel, so if inertia of the fan should cause it to become an over-running load, cavitation could occur in the motor or pump. To prevent cavitation, Baus says the hydraulic fan circuit contains an anti-cavitation valve — essentially a pilot-operated check valve controlled by backpressure in the circuit.

Additional features
Another trend in mobile hydraulics incorporated in the IT38G is to provide numerous oil sampling valves for fluid assessment. Making the oil sampling process easier speeds maintenance and increases the likelihood that machines will be well maintained.

To address the trend toward more environmentally friendly operation, Cat's Ecology Drains are used place of drain plugs. Ecology Drains incorporate a check valve that opens when a mating fitting is connected to the drain. This eliminates the potential for fluid spillage that can occur with drain plugs.

For more information, visit Caterpillar's website by clicking here.

Continue Reading

Handbook Simplifies Advanced Aspects of Mobile Hydraulic Controls

May 10, 2017
Author Brendan Casey lays out his hydraulics know-how that he acquired over 27 years in a simple handbook made for people that want to improve their skills in troubleshooting ...

BOOK 2, CHAPTER 12: Fluid Motor Circuits

March 18, 2009
Table of Contents

Sponsored Recommendations


May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

All-In-One DC-UPS Power Solutions

March 13, 2024
Introducing the All-In-One DC-UPS, a versatile solution combining multiple functionalities in a single device. Serving as a power supply, battery charger, battery care module,...

Motor Disconnect Switches

March 13, 2024
With experienced Product Engineers and Customer Service personnel, Altech provides solutions to your most pressing application challenges. All with one thought in mind - to ensure...

DC Power Solutions: Streamlined Power Supplies for Every Need

March 13, 2024
CBI All In One UPS Power Solutions combine the requirements for several applications in just one device which can be used as power supply unit, battery charger, battery care module...