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Kubota BX2350, BX2360, BX2660 - LA243 Front End Loader

Kubota LA243 Front End Loader - Hydraulic Circuit

1 - Bucket Control Valve, 2 - Bucket Cylinder, 3 - Boom Cylinder, 4 - Boom Control Valve, 5 - Control Valve Assembly, P - From Pump, P.B - To 3-Point Hydraulic System, T - To Tank, 1A - 1A Port, 2A - 2A Port, 1B - 1B Port, 2B - 2B Port

To operate the front loader, the hydraulic oil pressurized by the hydraulic pump flows from P port through the boom control valve (4) and the bucket control valve (1) to P.B. port or T port. Since relief valve is not equipped in the front loader control valve, the main relief valve in the tractor operates.

Kubota BX2350, BX2360, BX2660 - Control Valve Assembly

1 - Inlet and Outlet Section, 2 - Boom Control Valve, 3 - Bucket Control Valve, 4 - Power Beyond, P - P Port (From Pump), T - T Port (To Tank), A1,A2,B1,B2,P.B - Ports

The control valve assembly is composed of one casting block and four major section as shown above.

Inlet and Outlet Section

This section has P and T ports. The P port is connected to the OUTLET port of hydraulic block by the hydraulic hose. The T port is connected to the TANK port of hydraulic block by the hydraulic hose.

Boom Control Section

The boom control valve is of 4-position, 6-connection, detent, spring center type, consisting of a mono block valve housing, spool, load check valve, etc. This valve has A1 and B1 ports and controls oil flow to the boom cylinder.

Bucket Control Section

The bucket control valve is of 4-position, 6-connection, no detent, spring center type, consisting of a mono block valve housing, spool, load check valve, etc. This valve has A2 and B2 ports and controls oil flow to the bucket cylinder.

Power Beyond

This section has P.B. port which is connected to the INLET port of hydraulic block by the hydraulic hose, and feeds oil to the three point hydraulic control valve.

Kubota BX2350, BX2360, BX2660 - LA243 Loader Checking And Disassembling

Control Valve

Relief Valve Setting Pressure - The relief valve is not installed on this model. However the relief valve of the tractor hydraulic system is used as the relief valve of the front loader. Refer to hydraulic section. Relief valve setting pressure - 12.3 to 12.7 MPa (1780 to 1840 psi). Engine speed - Maximum. Oil temperature - 45 to 55C (113 to 131F).

Step and Battery

Remove the under panel. Disconnect the negative cable from the battery. Remove the valve covers. Remove the HST pedal and the step.

Disassembling Control Valve

1 - Dust Seal, 2 - Dust Seal, 3 - Load Check Valve, 4 - Spring, 5 - O-ring, 6 - Plug, 7 - Bolt, 8 - Plug, 9 - Seat, 10 - Spring, 11 - Ball, 12 - Stopper, 13 - Ring, 14 - Bolt, 15 - Plug, 16 - Seat, 17 - Spring, 18 - Ball, 19 - Stopper, 20 - Ring, 21 - Spool, 22 - O-ring, 23 - Back-up Ring, 24 - Collar, 25 - Spring Holder, 26 - Spring, 27 - Spring Holder, 28 - Valve Body, 29 - Spool, 30 - O-ring, 31 - Back-up Ring, 32 - Collar, 33 - Spring Holder, 34 - Spring, 35 - Spring Holder, A, C - Boom Control Section, B, D - Bucket Control Section

Remove the plugs (6) and take out the spring (4) and load check valve (3). Remove the seal plates (8), (15) with other parts inside plug (C), (D). Draw out the spools (21), (29) with other component parts (A), (B) from the valve body (28). Clean all parts with a suitable solvent, and dry with a lint-free cloth or air. Visually inspect all parts for damage. Install the spools to the valve body, not to damage the O-ring.

Kubota LA243 Loader - Bucket, Boom and Hydraulic Cylinders

Bucket and Bucket Cylinder

1-Pin, 2-Bucket Cylinder, 3-Bucket, 4-Pin

Remove the pins (4) the lower pin (1) and remove the bucket (3). Disconnect the hydraulic hoses from the bucket cylinder (2). Remove the upper pin (1) and remove the bucket cylinder (2). When installing the bucket cylinder (2), the hydraulic port should face inside and be careful of the direction of grease fittings.

Boom Cylinder and Hydraulic Tubes

1-Pin, 2-Pin, 3-Boom, 4-Boom Cylinder, 5-Side Frame, 6-Hydraulic Hose

Disconnect the hydraulic hoses from the boom cylinders (4). Remove the pins (2) and remove the boom cylinders (4). Disconnect the hydraulic hoses (6) with quick couplers at the control valve. Remove the pins (1) and remove the boom (3) from the side frame (5). Remove the hydraulic tubes from the boom (3). When installing the boom cylinders (4), the hydraulic port should face inside and be careful of the direction of grease fittings.

Piston Rod Assembly

Drain hydraulic oil from the cylinder, and secure the tube end of the cylinder in a vise. Unscrew the cylinder head with the adjustable gland nut wrench. Pull out the piston rod assembly from the cylinder tube. Visually inspect the cylinder tube for signs of scoring or damage. Insert the piston rod assembly to the cylinder tube, not to damage the piston seal on the piston. Install the cylinder head to the cylinder tube, not to damage the O-ring on the cylinder head.

Cylinder Head, Piston and Nut

1-Piston Rod, 2-Cylinder Head, 3-Piston, 4-Nut, 5-Wiper Seal, 6-Oil Seal, 7-O-ring

Secure the rod end in a vise. Unscrew the nut (4), and remove the piston (3) and cylinder head (2) from the piston rod (1). Visually inspect all parts for signs of scoring or damage. Insert the piston rod to the cylinder head, not to damage the wiper seal (5) and oil seal (6). Boom cylinder piston mounting nut - 150 to 180 Nm (111 to 132 ft-lbs). Bucket cylinder piston mounting nut - 350 to 400 Nm (259 to 295 ft-lbs).

Installing O-ring and Piston Seal

1 - Piston Seal, 2 - Slide Jig, 3 - O-ring, 4 - Piston

Place the slide jig (2) on the piston (4). Install the O-ring (3) to the piston using the slide jig. Install the piston seal (1) over the O-ring using the slide jig. Compress the piston seal to the correct size by installing the piston into the correcting jig (5). Do not turn (roll) the piston seal as you install it.

Piston Rod Bend

Place piston rod on V blocks. Set a dial indicator on the center of the rod. Turn the piston rod and read the dial indicator. If the measurement exceeds the allowable limit, replace it. Piston rod bend (Allowable limit) - 0.25 mm (0.0098 in).

Kubota LA243 Loader - Side Frames, Front Guard and Main Frames

Side Frames

1-Side Frame, 2-Pin, 3-Boom Assembly, 4-Boom Cylinder, 5-Pin

Remove the pins (2), (5). Remove the side frames (1) from the boom assembly (3) and the boom cylinder (4).

Front Guard and Main Frames

Remove the front guard. Remove the main frame mounting bolts and nuts from the tractor body. Remove the main frame. Main frame mounting bolt (M14) 147 Nm (108 ft-lbs).

Dismounting LA243 front end loader from Kubota BX2350, BX2360, BX2660 tractor

Side Frame

1-Stand, 2-Spring Pin, 3-Hydraulic Control Lever, 4-Protective Plug

Raise the boom until the stands (1) can be rotated. Stop the engine. Remove the spring pin (2) holding the stand (1) to the boom. Slide the stands (1) leftward and rotate it until the hole in the stand and pin on the boom are aligned. Then slide the stand (1) rightward and insert the spring pin (2). Start the engine and run at idle. Dump the bucket approximately 20 degrees. Lower the boom and raise the front wheels slightly. Lift the front wheels with the bucket. Do not attempt to lift the with the stand. Stop the engine. Remove the mounting pins from LA243 loader side frames and hold them in the plate of side frame. Start the engine and run at idle. Slowly move the hydraulic control lever (3) to rollback position to raise the loader side frames up and out of the receives of the main frames. Stop the engine. Slowly release all hydraulic pressure by moving the hydraulic control lever (3) in all directions. Disconnect the four hoses with quick couplers at the control valve and place them on the right side of the boom. Place the protective caps and plugs (4) on the quick coupler ends. Start the engine and slowly back the Kubota BX2350, BX2360, BX2660 tractor away from the loader.

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