2Purpose of LinesAll hydraulic lines are designed to transmit fluid from one place to another without leakingLines are built to withstand pressure, vacuum, and the hydraulic fluids used in the systemThere are two different types: Flexible and SteelAll lines have fittings on the end of them to connect to hydraulic devices
3Steel LinesSteel lines (tubing) is used when there is little vibration, limited space, no movement of the lines, and/or frequent replacement is neededSteel lines have two common type of connectors: JIC Flare and Flareless Compression
4JIC Flare FittingUsually has a nut, backup sleeve, and a 37° flare of the lineThis type is often used on the outside of cylinders on construction or farm equipmentCan also be used for return lines
5Flareless Compression Fitting A special type of ferrule that replaces the flareBites into metal to provide a positive seal that won’t slipCan be used for return linesAlso used for pressure lines on the frame
6Flexible LinesMany different types and materials used to make flexible linesAll flex lines are measured by the inside diameter of the lineCan use fraction measurement or dash sizeAll lines rated in working pressure, vacuum, or burst pressure
7Line SizesLines can be from 3/16” to 4” in size (Inside Diameter or ID)Dash size is determined by taking the number and making it the numerator of the fraction 16-3 hose size is 3/16” (3/16)-12 hose size is 12/16” or ¾” (12/16)Largest is –64 size (4”)
8Hose MaterialsMost hoses have an outer covering, a cloth or wire braid, and an inner material to prevent leakageCan be damaged by high temperaturesNeoprene or Buna-N used in most hydraulic hosesWire braids added to handle high pressures
10Hose Maintenance - Replacement Leaks at fitting or in hose. (Leaking fluid is a fire hazard.)Damaged, cut, or abraded cover. (Any reinforcement exposed.)Kinked, crushed, flattened, or twisted hose.Hard, stiff, heat cracked, or charred hose.
11Hose Maintenance - Replacement Blistered, soft, degraded, or loose cover.Cracked, damaged, or badly corroded fittings.Fitting slippage on hose.
12Hose RoutingMake sure to install hoses so that they are as close as possible to the componentThis keeps the line from being pulled offKeep a little slack in all lines to allow movement
13Hose RoutingMake sure the line flexes in and out rather than up and downMinimize movement if possible
14Hydraulic FittingsSeveral types of fittings used on hydraulic componentsNPTF (National Pipe Tapered - Fuel)JIC (37°)O-Ring BossO-Ring FlangeFlat Faced O-Ring (Forseal)
15NPTF Fittings The most commonly used on older equipment Seals by a tapered threadThe farther you turn it, the better it sealsStandard pipe thread can leak without the use of pipe sealant
16JIC Fittings The next most common fitting used Seals by seating an angled flared area against another angled areaCan leak if the seating area is scratchedHose end can be easily disassembled and repositioned
17O-Ring Boss Uses an O-Ring to seal the fitting Often has a jam nut that is used to compress the o-ringPermits turning an angled fitting to a desired position without leaking
18O-Ring Flange Fittings Primarily used on hose endsHas a round flat surface that uses an o-ring to seal it against the componentIs compressed by a separate backup flange that usually has 4 boltsCan leak if the flange is bent or the surface is scratched
19Flat Faced O-Ring Fittings Also called Forseal fittingsSimilar to JIC except the seating area is flat and the fitting has an o-ring in itCan leak if the face is deeply scratched or o-ring is badNewest type used on hydraulic equipment
20Fitting Installation - NPTF Inspect port components to ensure that male and female threads are free of nicks, burrs, dirt, etc.Apply sealant/lubricant to male pipe threads. With any sealant, the first few threads should be left uncovered to avoid system contamination. If Teflon tape is used, it should be wrapped 1-1/2 turns in a clockwise direction when viewed from the end.
21Fitting Installation - NPTF Screw Fitting into female pipe port to finger tight position.Wrench tighten fitting to the appropriate Turns From Finger Tight in the next chart, making sure the tube end of the shaped fitting is aligned to receive incoming tube or hose assembly.
22Turns From Finger Tight Chart Pipe Thread SizeTurns From Finger Tight24681216202432