How to Tap Hydraulic Lines

Anyone installing a front end loader or log splitter will need to tap into the hydraulic system to power those hydraulic cylinders that do the work. Some newer Kubota models come factory equipped with a hydraulic junction block which means interrupting the hydraulic circuit to draw power is fast and straightforward – simply connect your hoses. In this article we describe how to get started tapping the hydraulic circuit if you have an older Kubota or one not equipped with a junction block.

High and Low Pressure Lines
The first step is to locate the high and low pressure lines that run along the side of the transmission housing. The steel lines are two thicknesses – thin and thick. The thin line is the high pressure line which comes directly from the hydraulic pump. The pressure this line carries is significant!

High pressure hydraulic line found on the right side (when seated) of this B6200's transmission housing.

The thicker, fatter line, is the hydraulic suction line which draws hydraulic oil from the reservoir in the transmission and directs it to the hydraulic pump to be pressurized again on the high pressure line.

Steel suction line that returns oil from the reservoir back into the hydraulic pump to be repressurized.

Where to Tap In
The high pressure line is the line we interrupt to direct power to the control valve which sits in front of a loader or log splitter. The amount of line to remove is actually very small – perhaps only 2-3″. We are simply creating a bypass in the line that runs up to the control valve, through and out the control and then back down again to the other side of the high pressure line.

When the joystick valve is its neutral or normally open position, the hydraulic circuit acts as it did before – it just happens to be running up, through and back down again from the joystick control.

Tapped high pressure line shown in blue, the nipple fittings shown in red and flow of high pressure oil shown in green.

When cutting the steel line, be sure that no metal filings are left behind. Kubota models in and around the vintage of the B6200 shown in the video have a hydraulic suction filter which will catch most debris. If that filter gets plugged or goes many years without servicing, an operator will absolutely notice decreased performance, jittering and slow raising/lowering out of their loader. The rule of thumb in a hydraulic system is that cleaner is always better!

Nipple Fittings
You will need two nipple fittings (also known as hydraulic JIC fittings) for the tap – one for for each side of the high pressure line openings that we create when we remove the 2-3″ of line. The fittings are brazed onto the steel line which gives you an attachment point for your hydraulic hoses that run up/down from the control valve. The fittings we use are available from any hydraulic supply shop and cost about $5 each.

A nipple fitting brazed on the steel line which is then connected to by the hydraulic hose running up to the control valve.

The hydraulic pressure generated by a typical B Series ranges from 1450-1950 psi. L Series models have upwards of 2500-2600 psi of pressure running through that high pressure line so be sure those fittings are secure and inspect your hydraulic hoses for wear and tear.

Service Department Vic

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