When the rod and piston retract, fluid flows back to the reservoir, where the metal walls dissipate heat, cooling the fluid. The reduced pressure in the reservoir also helps trapped or dissolved air escape. If cylinders have to compress air bubbles, the system’s efficiency decreases.
Hydraulic systems use two main types of valves: directional control valves and pressure relief valves. Directional control valves regulate the fluid flow path within the system, while pressure relief valves safeguard the system by preventing pressure overloads and limiting the output force of rotary motors and cylinders. These valves open when pressure exceeds a set level, redirecting the oil back to the reservoir.
Fluid moves through a Automotive Lift Repair Florida hydraulic system via hydraulic hoses.
Types of Hydraulic Valves
Available at Automotive Lift Repair Florida, and check with your local store for more details:
– Converta Valve
– Detent Kit
– SCO Open Center / Detent Valve
– Open Center Valve
– Two Circuit Hydraulic Multi-Plier Valve
– SBS Series Valves
– Single Spool, 3-Position, 4 Way
– Double Spool, Both 3-Position, 4 Way
Q and A: Common Hydraulic Questions
A one-stage pump has a single maximum pressure and flow rate, commonly used with large engines like those in farm tractors. It’s used in applications like backhoes and manure loaders. A two-stage pump, usually found in smaller engines, initially provides high fluid volume for quick cylinder movement. Upon encountering resistance, a second set of gears produces high pressure for tasks like lifting or splitting, though the fluid volume decreases. For example, in log splitters, the pump moves the rod quickly until it begins splitting wood, at which point the speed slows but the force increases.
What’s the difference between a Automotive Lift Repair Florida single-acting cylinder and a double-acting cylinder?
A single-acting cylinder only works in one direction as pressure is applied to one side of the piston. It returns to its original position via load weight or a manual lever. A double-acting cylinder allows pressure to be applied to either side of the piston, enabling work in both directions.
Automotive Lift Repair Florida Tie-rod cylinders use four rods to hold them together, making them less expensive and easier to repair. Welded cylinders have a fixed end welded for increased strength and durability, suitable for high-pressure applications like log splitters.
An open system, common in older tractors and log splitters, uses a valve that connects all lines to the reservoir when in neutral, preventing pressure buildup. A closed system, found in modern equipment, uses a closed center valve that directs oil to an accumulator when the system is in neutral, storing it under pressure.
To convert, replace the short conversion plug with a closed center plug and the relief valve with a “no relief” plug. You’ll also need to add an outlet to the tank to handle oil from the return passage. Refer to the valve packaging for detailed instructions and part numbers.
NPTF fittings use tapered threads for sealing, while Automotive Lift Repair Florida JIC fittings use an O-ring. They should not be used interchangeably due to potential damage. Special adapters are available for converting between these types.
I.S.O. tips come in three types: ball, poppet, and pressure relief poppet. They are interchangeable with each other, with poppet tips offering a tighter seal. OEM old-style tips are unique to each manufacturer and require specific adapters for use with I.S.O. tips.
Can I use galvanized or brass fittings?
No, as these materials do not meet hydraulic system psi ratings and can flake, contaminating the oil.
Can Teflon tape be used on hydraulic fittings?
No, Teflon tape can flake and contaminate the oil. Use hydraulic-rated liquid Teflon sealant instead.
Can I use a standard valve for a single-acting cylinder?
No, a standard valve cannot release trapped oil, causing pressure overloads. Use a Converta valve designed for single-acting cylinders, but note it lacks a loadcheck and should not be used for load-lifting systems.
What Automotive Lift Repair Florida valve is needed for a loader?
Tractor Supply offers the SBAF2 double-spool valve with a floating detent for bucket contouring, and the SBA22 double-spool valve with spring-centered neutral for no “float.”
What valve is needed for a log splitter?
An open-center, single-spool valve with a preset 2000 psi relief and adjustable settings, rated for 30 GPM, is suitable.
What’s the difference between hydraulic oil and hydraulic fluid?
Hydraulic oil is refined petroleum oil with additives, while hydraulic fluid includes any non-petroleum-based liquids used in hydraulic systems, such as water-based or synthetic fluids. Always refer to your owner’s manual to avoid damaging seals or the system by using the wrong fluid.
Do I need to change the oil and filter?
Yes, to avoid increased temperatures and component damage. Refer to your owner’s manual for part numbers and change intervals.
How big should the reservoir be?
The reservoir should be three times the system capacity or 1.5 times the pump GPM rating, with enough surface area to allow heat dissipation.
What size hose do I need?
Choose hose size based on the system’s requirements. A 2-wire hose is recommended for pressures above 1800 psi, but always check manufacturer specifications.
Automotive Lift Repair Florida Hydraulic System Troubleshooting Guide
Assessing Poor Cylinder Performance
Check for:
– Oil leaks: Tighten fittings and repair or replace damaged seals or components.
– Low or no oil: Add oil to the reservoir.
– Viscous or cold oil: Allow time for warming.
– Dirty or clogged oil filter: Replace filter or element.
– Restricted oil line: Clean or replace lines.
– Worn or dirty pump: Clean, repair, or replace and check alignment.
– Dirty, damaged, or worn components or seals: Repair or replace as needed.
– Bent ram: Check for side pressure or improper mounting.
– Blown seals: Verify relief valve settings and use correct hydraulic fluid.
– Slipping or broken pump drive: Repair or replace belts and couplings.
– Leaking cylinder: Repair or replace seals and check valve holding capability.
– Excessive load: Verify load limits.
– Air in system: Check for leaks and purge air.
– Air leaks in pump section line: Repair or replace lines.
– Low pump drive speed: Increase engine speed as per manual.
– Improper adjustments: Adjust fittings and valves according to technical specifications.
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