How Does a Hydraulic Pump Work

The advantage of using a hydraulic machine is that more force and torque can be generated with relatively smaller sized machines without requiring a gear system. An important component of a hydraulic machine is the hydraulic pump. The supply of fluids like oil and water to the various components of the machine is accomplished by using hydraulic pumps. Their mechanism is based on the displacement of the fluid volume against a resistant load or pressure.

Hydraulic Machinery

The machines that make use of fluid power to carry out the necessary function or to do work in general are called hydraulic machinery. In these machines, a fluid having high velocity is distributed to the hydraulic motors and hydraulic cylinders through tubes of small diameters. This fluid is known as the hydraulic fluid, and it can be oil, water, gas, etc. Control on the fluid is exercised with the help of control valves that are controlled automatically. A hydraulic pump is an important component of the working process of a hydraulic motor.

Basic Concept of Hydraulic Pumps

Basically, pumps are meant to impart energy to anything flowing through them. They transfer the fluid from a low potential to a high potential as in heat pumps. When a fluid enters a hydraulic pump, it has some velocity of its own. Now, with the help of an external energy source the pump boosts the velocity of the fluid. The rotating parts inside the pump carry out processes like confining the fluid in a certain volume and displacing it to increase its energy. It should be noted that hydraulic pumps do not generate any pressure, and they simply render the fluid with more velocity.

Positive Displacement Pump Principle

In general, pumps can be classified as positive displacement pumps and non-positive displacement pumps. Hydraulic systems mostly make use of positive displacement pumps. As the article is on the processing of hydraulic pumps, working of the positive displacement pumps will be discussed further. Positive displacement implies displacing a fixed quantity of something. In the case of hydraulic pumps fluids, a positive displacement pump has an increasing opening on the suction side of the pump and a decreasing outlet on the discharge side. When liquid flows in to the pump, it is forced out with greater velocity as the discharge side outlet is decreasing in size. Positive displacement pumps can further be classified under subcategories according to the motion pattern of the enclosed volume forming parts. Operating a positive displacement pump against a closed valve on the discharge side should be avoided, and a safety valve on the discharge side of this pump is mandatory.

Types of Positive Displacement Pumps

Reciprocating Pumps
This is the most basic type of positive displacement pump. In a reciprocating positive displacement pump, the moving part that is the piston, has a reciprocating motion. The discharge in this pump is pulsating and varies only when the speed of the pump is changed. The reason being that the intake is in constant volumes. Reciprocating pumps are often implemented for sludge and slurry. The two types of reciprocating pumps are plunger pumps and diaphragm pumps.

Metering Pumps
These pumps are used for precisely controlling very low flow rates. Flow rates are generally less than ½ gallon per minute. They are usually used to control additives to the main flow stream. These pumps are also called controlled volume pumps. Metering pumps have types such as diaphragm and packed plunger. Unlike the reciprocating positive displacement pumps, the metering pumps are meant to be used for clean fluids and impurities that can clog the valves of the pump.

Rotary Pumps
The rotary positive displacement hydraulic pumps come in the following types - the gear pumps, lobe pumps, vane pumps, progressive cavity pumps, peripheral pumps, and screw pumps. In these pumps, rotary motion carries the liquid from the pump inlet to the pump outlet. The fluid gets trapped in the closed casing of the rotary pump and is discharged in a smooth flow.

The basic information on the mechanism of hydraulic pumps, and their various types, has been provided above to give you an introduction to the subject. Hydraulics in itself, is a vast field and various books are available that will provide you more in depth information on the it.

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Rebuild a Hydraulic Cylinder

Hydraulic systems are widely used in agriculture, construction and manufacturing industry. Bulldozers, cranes, tractors, elevators and all such heavy machines use hydraulics. Hydraulic hybrid vehicles are some of the newest developments in this field of technology. Hydraulics is an applied science, which exploits the mechanical properties of fluids to build hydraulic systems that can perform heavy duty mechanical jobs with precision. Hydraulic systems offer power with precise control and versatility. At the core of every hydraulic system is the hydraulic cylinder. It is the central component on which all hydraulic systems are dependent. Therefore, one must learn rebuilding these cylinders, as it saves money and valuable time.

Construction and Working

Any hydraulic system is made of two parts; the hydraulic pump that generates the pressure and the hydraulic cylinder that delivers the mechanical action in response to pressure. The cylinder is a barrel fitted with a piston, which fluidly moves back and forth. The cylinder barrel is of course sealed from both ends.

The piston divides the barrel body into two parts; the rod end, which is the side from where piston enters the barrel body and the other side, which is capped, called the cap end. The piston is driven back and forth, by the hydraulic fluid, which is mostly oil, introduced by the hydraulic pump. The piston has sliding rings and seals, which prevent the leakage of fluid from one part of the piston compartment, to the other part. The piston is connected with appropriate mounting arrangement. It conveys piston motion to appropriate moving part of the machine, which carries the load.

The idea behind every hydraulic system working is simple. The pressure applied at one point is conveyed to other point by the use of an incompressible fluid which is usually oil. So when the pump pushes oil into the piston chamber, from the cap side, the piston is lifted up. When oil is sucked back by the hydraulic pump from the chamber, the piston gets pushed down. This is how a hydraulic system works by conveying force through an incompressible fluid. By using pistons of different surface areas, force multiplication can be achieved. A heavier load can be lifted up by relatively lesser force, using this principle!

Repair Tips

Here are some common problems that can break a cylinder or cause its malfunctioning. I will outline the possible solutions that can help you rebuild or repair your cylinder. Read instruction manuals for the machine supplied by the manufacturers carefully, before going ahead.

Problem 1: The cylinder is cracked or piston rod is bent

Solution: If on observation, you see the cylinder rod is bent or the cylinder barrel is cracked, there is pretty much nothing you can do. It's time to replace the cylinder. Forging a new barrel or straightening the piston rod is beyond your capacity. So if this is the case, repairing the cylinder is not possible. In such a case, only a specialized repair shop can rebuild the cylinder for you, as a customized new shaft may need to be forged and the cylinder bore may need to be honed.

Problem 2: The seal is broken

Solution: If the shaft seal is broken, the pressurizing fluid leaks and loses pressure, impairing working of the cylinder. It can be replaced. However, an opening of the entire cylinder assembly is necessary. Let us see how we can go about it. Obtain a diagram of the cylinder if possible, as it will help you in reassembly. These diagrams can be had from the equipment manufacturers and you can also carry a printout. You can order a standard repair kit for your cylinder which is supplied by the manufacturing company. It includes spare cylinders, spare seals, O-rings and other spare parts according to the number and type of cylinders in your machine.

The assembly of the cylinder varies with machine type. Locate the seal position first. Mostly, you will find it around the shaft on one end. The shaft entry end can be accessed by unscrewing the lid from that side. You may need to unscrew the bolts, to remove the cover. Then loosen the pipes or valves that transmit the hydraulic fluid into the chambers which will release pressure. This will enable you to remove the shaft which otherwise cannot be removed due to hydraulic pressure. Handle the shaft carefully and take care that you do not scratch it. Detach the piston from the shaft and replace the seal with the spare one from the repair kit. Make sure that the seal is aligned rightly. Oil all parts after fitting and reassemble everything in exactly reverse order.

Problem 3: Piston Rings are damaged

Solution:If the piston rings are damaged, then they can be replaced too, by the same disassembling procedure, as for the above problem. The piston rings need to be removed and replaced very carefully. Oil the rings and cylinder assembly, before putting back everything together.

If you have a multiple cylinder arrangement, things are more complicated. It is better to consult a qualified technician before going ahead. Always remember one rule, while you are solving mechanical problems, do not proceed without a reason to take a particular action. Also, study the assembly and causative framework of the machine before going for repair. This repair can be a good learning experience for anyone who loves machine design.

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E-OLSS Hydraulic Pump

Introduction.
The E-OLSS (Electronic – Open centre Load Sensing System) is an energy saving system to reduce fuel consumption by means of controlling the swash plate angle. 
A Variable-displacement swash plate piston pump is used with an OLSS control valve. For this combination to work there is a series of valves mounted on the pump to sense the different machine operating demands

Effective Use of Engine Horsepower
For optimum out-put of the machine its important for the engine to maintain a set speed.
As the load in the hydraulic system changes the discharge amount from the pump needs to
be adjusted.
The valves mounted on the hydraulic pump that sense the change in working conditions.
1.Servo Valve.
2.CO valve (Cut-Off control)
3.NC valve (Neutral control).
4.TVC valve (Torque Variable Control)
All the pump control valves and servo piston are operated by charge pump pressure.

Servo Valve.
The Servo Valves controls the pump out-put from the signals received fromTVC, CO and NC
valves.

The arm is connected into the servo piston and senses the servo piston position, this will
allow the pump to discharge the volume amount corresponding to signal pressure.

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Fuel control dial

Function
• The fuel control dial is installed under the monitor
panel, and a potentiometer is installed under the
knob. The potentiometer shaft is turned by turning
the knob.

• As the potentiometer shaft is turned, the resistance
of the variable resistor in the potentiometer
changes and a throttle signal is sent to the
engine throttle and pump controller.
The hatched area in the graph shown at right is
the abnormality detection area.

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Komatsu Launches New HM400-3 Articulated Truck

Komatsu America Corp. introduces the HM400-3 articulated truck. With a net horsepower of 469 hp (350 kW), the HM400-3 is powered by a Komatsu SAA6D140E-6 engine and is EPA Tier 4 Interim and EU Stage 3B emissions certified. Komatsu leveraged its leadership in technology and innovation—building on its proven Tier 3 engine platform—to design an environmentally friendly engine that increases power while decreasing fuel consumption.
Every Komatsu Tier 4 Interim construction machine comes standard with Komatsu CARE™ complimentary factory scheduled maintenance for 2,000 hours or the first three years, and includes two complimentary KDPF exchanges within the first 5 years. The Komatsu CARE program covers all new Komatsu Tier 4 Interim equipment, whether rented, leased or purchased.
The HM400-3 features a maximum gross vehicle weight (GVW) of 162,569 lbs. (73,740 kg), hauling up to a 44.1 US ton (40 metric ton) payload at its maximum ground speed of 34.7 mph (55.9 kph). Improved operating performance, lower fuel consumption, improved operator comfort and enhanced serviceability are features of the HM400-3 that provide maximum productivity and lower operating costs.
The HM400-3 is equipped with the latest KOMTRAX® technology, which sends machine operating information to a secure website utilizing wireless technology. Data such as daily fuel consumption, machine utilization, operating hours, location, cautions and maintenance alerts are relayed to the web application for analysis. The KOMTRAX fleet monitoring system increases machine availability, reduces the risk of machine theft, allows for remote diagnosis by the distributor, and provides a wealth of other information to drive business efficiency and productivity.
Special features of the new HM400-3 include:
• EPA Tier 4 Interim and EU Stage 3B Emissions Certified Engine
Built upon proven Tier 3 technology, the SAA6D140E-6 engine provides increased horsepower while lowering fuel consumption. The Komatsu Tier 4 Interim engine uses an advanced electronic control system to manage airflow rate, fuel injection, combustion parameters, and after-treatment functions to optimize performance, reduce emissions, and provide advanced diagnostic capability.
As a leader in hydraulic technology, Komatsu has also developed a hydraulically actuated Variable Geometry Turbocharger (KVGT) and Exhaust Gas Recirculation (EGR) valve, resulting in better precision and air management as well as longer component life. The Komatsu Diesel Particulate Filter (KDPF) has an integrated design that will not interfere with daily operation but will keep the operator aware of its status.
• Improved Operation
The HM400-3 features the new Komatsu Traction Control System (K-TCS). The K-TCS system automatically provides optimum traction when operating in soft ground conditions. As ground conditions worsen, speed sensors located on four wheels detect tire slippage, and automatic application of the inter-axle differential lock occurs. If tire slippage continues to be detected, four independent brakes can be applied to slipping wheels to regain traction.
The HM400-3 is enhanced with K-ATOMiCS—Komatsu Advanced Transmission with Optimum Modulation Control System. K-ATOMiCS offers a six-speed, fully automatic transmission that uses an advanced electronic system to eliminate shift shock and torque cutoff to improve operator and engine efficiency. The electronic system automatically selects the ideal gear based on vehicle speed, engine rpm and the shift position chosen, resulting in powerful acceleration, smooth down shifting and synchronized engine speed when climbing slopes. K-ATOMiCS ultimately minimizes operator fatigue, keeps the load in the body and increases productivity.
A large automatic retarder allows the operator to select the optimum operating speed on downhill travel and fully loaded hauls, eliminating acceleration generated by the grade of the slope.
• Increased Payloads
Through body design optimization the HM400-3 features increased body capacity and payload. The low 10’5”” (3164 mm) loading height easily matches with 40 ton to 60 ton hydraulic excavators or 5.5 yd³ to 7.5 yd³ wheel loaders. In addition, the two single-staged body lift cylinders provide a 70-degree dump angle.
• Enhanced Operator Environment
The new cab design provides a comfortable and quiet work environment for maximum operator can maximize productivity. The ROPS/FOPS Level 2 certified cab features a new designed rounded front dash panel with easy-to-reach switches. The dashboard has been redesigned and the high back, heated air ride seat with 3-point seat belt has been relocated to improve visibility. An auxiliary input has also been added to connect an MP3 player or other device along with two 12-volt ports that have been incorporated into the cab.
A new high resolution 7” LCD monitor features enhanced capabilities and displays information in 25 languages for global support. Using the monitor, the operator can easily modify settings for items such as the Auto Idle Shutdown or the auto-reversing fan; check operational records, such as driving history or fuel consumption; monitor the KDPF or check for when the next maintenance interval is required.
The monitor also offers the operator the option of using the ECO guidance function, which provides operational tips to reduce fuel consumption. A rear view monitor system with a separate 7” LCD monitor is standard with every machine and is mounted on the right hand side of the console for operator convenience.
• Convenient Maintenance and Serviceability
To reduce costly downtime, the HM400-3 provides easy service access. The new model features a newly designed engine hood for easy access, increased cooling capacity, and two standard hydraulically driven auto-reversing fans to help keep the radiator and charge air cooler clean.
The truck is equipped with the exclusive Komatsu EMMS (Equipment Management Monitoring System) that has enhanced diagnostic features that give the operator and technicians greater monitoring and troubleshooting capabilities. EMMS also continuously monitors all critical systems, preventative maintenance, and provides troubleshooting assistance to minimize diagnosis and repair time.

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Komatsu Corp. Launches New WA470-7 Wheel Loader

Rolling Meadows, IL, October 15, 2012 — Komatsu America Corp. introduces the WA470-7 wheel loader. With a net horsepower of 272 hp (203 kW), the WA470-7 is powered by a Komatsu SAA6D125E-6 engine and is EPA Tier 4 Interim and EU Stage 3B emission certified. Built upon a proven Tier 3 engine platform, Komatsu has leveraged its leadership in technology and innovation to design a more environmentally-friendly engine that increases power while decreasing fuel consumption by approximately 8 percent, compared to the WA470-6.
Weighing in at 52,007 pounds (23,590 kg), the WA470-7 features improved efficiency, lower fuel consumption, improved operator comfort, and enhanced serviceability to maximize productivity while lowering operating costs.
The WA470-7 is equipped with the latest KOMTRAX® technology, which is fully integrated with Komatsu’s Tier 4 technology. Machine operating information such as operating hours, fuel consumption, location, cautions and maintenance alerts are wirelessly relayed to a secure website for analysis.  The KOMTRAX fleet monitoring system results in increased machine availability and, reduced risk of machine theft when compared to machines not equipped with KOMTRAX. The technology also allows for remote diagnosis by the distributor and provides a wealth of other information to drive business efficiency and productivity.
New features of the WA470-7 include:
• EPA Tier 4 Interim and EU Stage 3B Emission Certified Engine
Built upon proven Tier 3 technology, the SAA6D125E-6 engine provides lower emissions while also lowering fuel consumption. The Komatsu Tier 4 Interim engine uses an advanced electronic control system to manage air flow rate, fuel injection, combustion parameters and aftertreatment functions to optimize performance, reduce emissions, reduce fuel consumption and provide advanced diagnostic capability.
As a leader in hydraulic technology, Komatsu has also developed a hydraulically actuated Komatsu Variable Geometry Turbocharger (KVGT) and an Exhaust Gas Recirculation (EGR) valve, resulting in better precision and air management as well as longer component life. The Komatsu Diesel Particulate Filter (KDPF) has an integrated design that will not interfere with daily operation but will keep the operator aware of its status.
The WA470-7 also features Komatsu Smart Loader Logic (KSLL), which provides optimal engine torque for the job required. KSLL allows for fuel reduction by decreasing engine torque when the loader isn’t working hard, such as when it is driving with an empty bucket. KSLL functions automatically with machine operation and results in saving fuel without decreasing production.
• Large Capacity Torque Converter with Lock-Up
The WA470-7 has a newly designed Komatsu Large Capacity Torque Converter with Lock-Up as a standard feature. This provides improved acceleration, faster hill climb ability, a higher top speed and lower fuel consumption. The Lock-Up function activates in 2nd, 3rd and 4th gears giving the machine a maximum ground speed of 23.8 mph (38.3 kph).
The wheel loader has greater productivity in V-cycle applications because of the increased tractive effort. The faster hill climbing ability allows the WA470-7 to up-shift gears faster because of improved acceleration. The wheel loader can also achieve higher gear ranges and maintain higher ground speeds when working in load-and-carry applications. In most applications, production is increased and fuel consumption reduced, resulting in improved fuel efficiency.
• Enhanced Operator Environment
The new cab provides a more comfortable and quieter work environment so the operator can maximize productivity. The front glass has been lowered and the dashboard has been redesigned to improve visibility. Electronic Pilot Control (EPC) levers and an F-N-R switch are part of a redesigned seat-mounted right hand console. An auxiliary input has also been added to connect an MP3 player or other device along with two 12-volt ports that have been incorporated into the cab.
A new high resolution 7” LCD monitor features enhanced capabilities and displays information in 25 languages for global support. Using the monitor, the operator can easily modify settings for items such as the Auto Idle Shutdown or the auto-reversing fan. The operator can also check operational records, such as working hours or fuel consumption; monitor the KDPF soot load; or check how much time is required before the next maintenance interval. In addition, the monitor offers the operator the option of using the ECO Guidance (economy) function, which will provide operational tips to reduce fuel consumption. A separate high-resolution back-up camera is standard with every machine and is mounted on the right hand side of the console for operator convenience.
• Customer peace of mind is standard because of Komatsu CARE®
Komatsu remains focused on lowering the customer’s ownership costs by engineering machines with increased fuel efficiency and productivity. Komatsu CARE® complimentary scheduled maintenance is standard on all WA470-7 wheel loaders for three years or 2000 hours (whichever occurs first). Services are performed by factory certified technicians using only Komatsu genuine parts and fluids. Also included are two complimentary KDPF exchanges at 4,500 hours and 9,000 hours within the first five years.
• Convenient Maintenance and Serviceability
The WA470-7 provides easy service access in order to reduce downtime. The new model has increased cooling capacity, wider cooling fin spacing and a standard auto-reversing fan to help keep the radiator clean. The machine is equipped with the exclusive Komatsu Equipment Management Monitoring System (EMMS), which provides enhanced diagnostic features that give the operator and technicians greater monitoring and troubleshooting capabilities. EMMS continuously monitors all critical systems, as well as the planned preventative maintenance schedule, and provides troubleshooting assistance to minimize diagnosis and repair time.
Note: All comparisons and claims of improved performance made herein are made with respect to the prior model, WA470-6, unless otherwise stated.
Komatsu America Corp. is a U.S. subsidiary of Komatsu Ltd., the world’s second largest manufacturer and supplier of construction, mining and compact construction equipment. Komatsu America also serves forklift and forestry markets. Through its distributor network, Komatsu offers a state-of-the-art parts and service program to support the equipment. Komatsu has proudly been providing high-quality reliable products for nearly a century. Visit the website at www.komatsuamerica.com/ for more information.

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Komatsu PC4000 Hydraulic Shovel Offers Reliability and Durability

MINExpo 2012, September 24, 2012 — Komatsu’s PC4000 hydraulic shovel, with an operating weight between 855,500–879,800 lbs. (388-399 M. tons) and a bucket capacity of 29 yd3 (22 m³), is designed with the goal of helping mining customers move more material in less time for reduced costs per ton and increased profits. A powerful Komatsu SDA16V160E-2 diesel engine and four circuit advanced “Hydropilot” hydraulics are two of the major improvements to this model. Blending innovative technology and engineering, Komatsu’s PC4000 stands up to the rugged-use of today’s mining applications. The Komatsu SDA16V160E-2 diesel engine has a rated power of 1875 HP (1400 kW). The shovel’s low engine emission levels meet EPA regulations TIER II and the time saving oil management system is fitted as standard on all machines. Electric drive 4,16 kV – 7,2 kV, 50 or 60 Hz, is also available.
• Productivity Moves More Tons Per Hour
With backhoe break-out force of 250,000 lbs. (1155kN) and loading shovel crowd force of 300,000 lbs. (1330 kN), the Komatsu shovel is designed with the highest digging forces in its class to increases mine productivity. All cylinders are mounted in the shadow of the attachment’s steel structure for component protection. A wide-range of wear packages and buckets are available to suit various densities and applications. Different track shoes can be selected to meet various ground conditions. Komatsu’s PC4000 is recommended for use with trucks ranging from 150 to 240 US tons.
• Large Cab for Operator Comfort
The PC4000 features an insulated cab on multiple viscous mounts for reduced noise and vibration. The cab has a deep wide front window with the operator positioned and seated on a multi-adjustable air suspension seat for improved operator comfort and visibility. The cab has A/C climate control with pressurized filtered air ventilation. An optional back up A/C or heater is available.
• Advanced Hydraulics
The four circuit advanced “Hydropilot” hydraulics on the PC4000 deliver precision control and extended reliability. The single engine is connected to a gearbox driving four identical Komatsu main pumps that draw hydraulic oil from an unpressurized hydraulic tank. The open circuit hydraulic system is fitted with swing out oil coolers and monitored filtration which contributes to enhancement of machine efficiency and operating life over previous versions of the PC4000.
• Easy Maintenance
The PC4000’s maintenance-friendly design provides quick access to major components for easier maintenance. Access to all major service points are at the machinery’s house level and there is also ground-level access to the hydraulically-powered swing-down service arm with WIGGINS® connections.
The PC4000 is equipped with KOMTRAX Plus® (former VHMS) technology, which sends machine operating information to a secure website utilizing wireless technology. Without any additional IT expense, data such as operating hours, component trends, machine utilization (including idle time and fuel consumption) and production information are relayed to the web application and made available on-line for analysis. In real time, the KOMTRAX Plus® fleet monitoring system monitors machine availability, allows for remote diagnosis of machine issues, and provides a wealth of other information to drive business efficiency. In addition to KOMTRAX Plus, an interface for the connection of the Modular Mining System is incorporated.
Komatsu America Corp. is a U.S. subsidiary of Komatsu Ltd., the world’s second largest manufacturer and supplier of construction and mining equipment. Komatsu America also manufacturers and supplies specialized equipment for the forestry, materials handling and numerous other industries. Through its distributor network, Komatsu offers a state-of-the-art parts and service program to support its equipment. Komatsu has been providing high-quality reliable products for nearly a century. Visit us at http://www.komatsuamerica.com/ for more information.

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