Hydraulic Pumps

About Hydraulic Pumps and Hydraulic Pump Manufacturers Including: Electric Hydraulic Pump, Hydralic Pumps, Hydraulic Gear Pump, Hydraulic Hand Pump & Hydraulic Water Pump.

Hydraulic pumps are extremely basic and capable devices designed to move liquid by pressure or suction. Hydraulic pumps are used to transfer energy and are powered by an energy source that initializes the pump but has no part in the pumping action itself. The kinetic energy of the fluid is used to force a small part of liquid that is under high pressure to a reservoir, called the pump outlet, which is at a higher level. Commonly, a small diameter piston is pushed against an uncompressible fluid, such as oil. The smaller piston causes the oil to move a second, larger piston on the opposite side of the system, multiplying the force. Hydraulic multiplication factors make pumps useful in many applications that require great strengths, including automobile braking systems, dump trucks and construction shovels/excavators.
 
Hydraulic pump manufacturers produce hydraulic pumps in different varieties, sizes, flow rates and power ratings. If the cylinder of the hydraulic pumps is expected to constantly raise a heavy weight, a single piston pump or double-acting pump is appropriate. In applications that initially have little to no resistance but require high force later on, a two-speed dual piston pump will suffice. Hydraulic pumps with a 4-way valve are ideal for applications that call for a double-acting cylinder, which exerts force in either direction. Hydraulic pump manufacturers may need to know the weight of the load being lifted by and the piston diameter of the cylinder, the number of cylinders lifting the load and the travel length (stroke) of the cylinder, in order to determine the appropriate type of pump for the application.
 
Pressure capacities are important factors when purchasing from hydraulic pump manufacturers. The load is actually what causes the pressure on the fluid, not the pump itself. The rotary action of the pump simply moves the fluid, causing flow. Hydraulic pumps pressure rating is determined by the capability of the pump to withstand pressure without internal leakage or damage to the pump components. If simple or moderate work is expected, low- and medium-pressure pumps will do just fine. On the other hand, if a pump will be used for large construction equipment, a high pressure system will most likely be necessary.
 
It is difficult to predict when hydraulic pumps will fail. However, new diagnostic technology has been developed that claims to do just that. The discharge pressure of hydraulic pumps is directly measured to accurately predict failure and the remaining life of the pump. This technology improves on the common detection methods of using vibration signals, which are affected by environmental interference, by measuring the ripples on the surface of the fluid, which are not affected by external sources. By easily extracting a “feature signal” from the pump discharge pressure in real time, it is able to predict failure within 50 to 100 hours, which leads to improved safety and significantly reduced or eliminated downtime. The system can be economically integrated into new or existing hydraulic pumps without much modification.

Hydraulic Pumps and Hydraulic Pump Manufacturers Images Provided by Star Hydraulics, Inc.

Types of Hydraulic Pumps

• Air hydraulic pumps are energy-saving pumps that are operated by a compressed air source and require no energy to maintain system pressure. In both the single- and two-stage air hydraulic pumps, air pressure is simply converted to hydraulic pressure, and they stall when enough pressure is developed.
  
• Axial piston pumps have pistons that make the strokes in the same direction along the centerline of the cylinder block.
  
• Centrifugal pumps are non-positive displacement pumps that are used in hydraulics requiring a large volume of flow. Centrifugal pumps operate at fairly low pressures and are either diffuser or volute types.
  
• Electric hydraulic pumps use hydraulic cylinders to provide electric power to machinery.
  
• Fixed-displacement pumps are pumps whose output can only be altered by changing the drive speed.
  
• High pressure pumps are pumps that operate at extremely high pressures. High pressure pumps operate in the range of 3,000 to 70,000 psi.
  
• Hydraulic gear pumps have intermeshing gears that displace fluid, creating mechanical power.
  
• Hydraulic hand pumps are manually operated to pressurize a hydraulic system. Hydraulic hand pumps are often used to calibrate instruments.
  
• Hydraulic pumps convert hydraulic energy to mechanical power.
  
• Hydraulic ram pumps require virtually no maintenance, as they have only two moving parts. Water from an elevated water source enters one of two chambers through a relatively long, thick pipe, developing inertia as it moves down to the second chamber, which starts the pump.
  
• Hydraulic water pumps use hydraulic power to move water from one place to another.
  
• Nonpositive-displacement pumps discharge liquid in a constant flow.
  
• Positive displacement pumps discharge liquid volumes at separate periods.
  
• Radial piston pumps use pistons that are arranged in a design similar to wheel spokes and are situated in a small cylindrical block.
  
• Reciprocating pumps depend on reciprocating motion in order to transmit fluid from the inlet side to the outlet side.
  
• Rotary pumps are a type of positive-displacement pump that use rotational motion to transfer liquids from the pump inlet to the outlet.
  
• Two-stage electric hydraulic pumps are pumps in which the clamps and cylinders are quickly extended by high flow at low pressure in the first stage of operation. In the second stage, piston pumps build pressure to a preset level and then maintain that level.
  
• Two-stage pumps are composed of two separate pump assemblies that are contained in a single housing.
  
• Variable-displacement pumps have cylinder sizes that are changeable.

Hydraulic Pumps Terms

Accumulator – A container that stores fluid under pressure and is utilized as a source of energy or to absorb hydraulic shock. Accumulator types include piston, bladder and diaphragm.
 
Cavitation – A circumstance that occurs in pumps when existing space is not filled by available fluid. Cavitation will deteriorate the hydraulic oil and cause erosion of the inlet metal.
 
Closed-Center System – A system in which the pump continually operates against a load, even in the neutral condition.
 
Cylinder – A hydraulic actuator constructed of a plunger or piston inside a cylindrical housing. The piston or plunger operates because of pressurized liquid.
 
Displacement – The amount of liquid transferred from the inlet of the pump to the outlet in a single revolution. Displacement can be fixed or variable.
 
Flow Rate – The amount of liquid volume that passes a given point in a given time. Flow rate is commonly measured in gallons per minute (gpm).
 
Head – Vertical distance measured between two stages in a liquid.
 
Hydraulic Actuator – The piece of machinery that receives pressure from the energized fluid and then converts it to motion and mechanical force.
 
Hydraulic Filter – A device that filters out impurities in the liquid used to create mechanical energy.
 
Hydraulic Hoses – A relatively thick hose that transfers liquids to and from hydraulic pumps.
 
Hydraulic Power Unit – Any device used to create kinetic energy within a hydraulic system. Motors and manual energy are both sources of power in hydraulic power units.

Hydraulic Tester – A device used to troubleshoot and check hydraulic powered system components.
 
Hydraulic Valve – A device used to regulate water distribution in hydraulic applications.
 
Hydraulics – The science dealing with the transmission of force through the medium of a contained fluid.
 
Oil – A slippery and viscous liquid that is not miscible with water. Oil is often used in conjunction with hydraulic systems because it cannot be compressed.
 
Open-Center System – A system in which the yield of the pump has a free-flow passageway back to the reservoir, while in the neutral condition.
 
Piston – A device used for converting hydraulic power to mechanical energy. In hydraulic pumps, the piston is responsible for pushing down and pulling up the ram.
 
Pump – A mechanical device that transports liquids and gases by suction or pressure.
 
Ram – A hydraulic mechanism that uses the kinetic energy of a flowing liquid to force a small amount of the liquid to a reservoir contained at a higher level.
 
Resistance – In hydraulics, the condition engendered by an obstruction or restriction in the flow path.
 
Seal – A fastener designed to provide a perfect and tight closure. Seals prevent environmental materials from contaminating hydraulic assemblies.
 
Valve – A device used to regulate the amount of hydraulic or air flow. In the closed position, there is zero flow, but when the valve is fully open, flow is unrestricted.
 
Velocity Pressure – Pressure in a hydraulic system caused by kinetic energy.