Specifications, Service and Repair of Farm and Lawn Tractors

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Kubota BX23, BX23S - LA340 Loader

Kubota BX23, BX23S - Hydraulics Checking

Hydraulic circuit - The hydraulic system of Kubota BX23, BX23S tractor and front loader has a hydraulic pump, control valve for front loader, 3 point hitch system and other components. This system has the following functions: Oil is supplied by hydraulic pump which is operated by pump drive shaft in the transmission case. As the pump drive shaft is connected to the propeller shaft, hydraulic pump starts operating when engine starts. The hydraulic pump supplies the high pressured oil to control valve for front loader, control valve for 3 point hitch system, power steering controller, PTO clutch valve and hydrostatic transmission after dividing oil flow by flow priority valve.

Outline of one touch front loader

One touch front loader is adopted to BX80 series tractor. The operator can attach and disconnect the front loader quickly and safely without getting down from the tractor. One lever quick touch 4 lines coupler - The quick touch coupler allows to attach and remove the quick coupler. The quick coupler is divided to the upper part and the lower part. The upper part consists of the quick coupler lever and the mobile quick coupler with four hydraulic hoses. The lower part consists of the quick coupler base with four hydraulic pipes. It is installed to the loader main frame. Non-spill structure is adopted in the couplers on the quick coupler base to protect the oil leakage from the hydraulic oil line.

Operating control lever (Front remote hydraulic control system)

Turn the front-hydraulic-valve-main-switch on. Push the front-hydraulic-valve-main-switch to engage the front-hydraulic-valve. The light on the front-hydraulic-valve-main-switch will illuminate to indicate that the front-hydraulicvalve is on and to enable the activation switch and operation of the lever. Turn the activation switch on or off. When operating the lever to left side with pressing the activation switch, hydraulic oil will come out of port 1 and return through port 2 as long as operating the lever to left side with pressing the activation switch. When operating lever to right side with pressing the activation switch, hydraulic oil will come out of port 2 and return through port 1 as long as operating lever to right side with pressing the activation switch. Turn the front-hydraulic-valve-main-switch off. Push the front-hydraulic-valve-main-switch again to disengage the front hydraulic valve. The light of the front-hydraulic-valve-main-switch will turn off.

Checking front hydraulic valve main switch continuity

Disconnect the front hydraulic valve main switch connector. Measure the resistance with an ohmmeter between terminal RB and terminal B. If 0 ohm is not indicated, replace the front hydraulic valve main switch. Checking connector voltage of front hydraulic valve main switch - Disconnect the front hydraulic valve main switch connector. Turn the main switch on. Measure the voltage between terminal RB and terminal B. If the measurement differs from the battery voltage, wire harness is damaged. Checking relay - Remove the relay. Apply battery voltage across terminals 3 and 4, and check for continuity across terminals 1 and 2. If continuity is not established, renew the relay.

Kubota BX23, BX23S - Boom cylinder and bucket cylinder

Both boom cylinder and bucket cylinder consist of a head, cylinder tube, piston rod, piston, and other parts as shown in the figure below. They are single-rod double acting cylinder in which the reciprocating motion of the piston is controlled by hydraulic force applied to both of its ends.

Bucket, boom and hydraulic cylinders

To mount an attachment, pull the quick attach coupler handles to the unlatched position to release the latching pins. Move the quick attach coupler handles all the way up to ensure that the latching pins are fully retracted. Position the Kubota BX23, BX23S tractor squarely in front of the attachment and tilt the quick attach coupler forward with the bucket cylinder. Ease the quick attach coupler mounting plate into the saddle of the attachment. Roll the quick attach coupler back using the bucket cylinder and raise the boom slightly. The back of the attachment should rest against the front of the quick attach coupler mounting plate, and the weight of the attachment should be supported by the loader. When the attachment is properly seated in the saddle and against the front of the quick attach coupler mounting plate, turn off the engine and set the parking brake.

Push the quick attach coupler handles to the fully latched position. Verify that both latching pins are completely engaged in the base of the attachment. When pushing the quick attach coupler handles into the locked position, visually verify that the latch pins rotate completely and are located underneath the stop of the quick attach coupler. When attaching different attachments, visually inspect for broken or damaged pins. If broken or damaged pins are found, replace before using.

Removing bucket cylinder

Disconnect the hydraulic hoses from the bucket cylinder. Remove lower pin and upper pin and remove the bucket cylinder. Removing boom cylinder and hydraulic tubes - Disconnect the hydraulic hoses from the boom cylinders. Remove the pins and remove the boom cylinders. Disconnect the hydraulic hoses with quick couplers at the control valve. Remove the pins and remove the boom from the side frame. Remove the hydraulic tubes from the boom. Removing piston rod assembly - Drain hydraulic oil from the cylinder, and secure the tube end of the cylinder in a vise. Remove the cylinder head with the adjustable gland nut wrench. Pull out the piston rod assembly from the cylinder tube. Removing cylinder head, piston and nut - Hold the rod end in a vise. Remove the nut, and remove the piston and cylinder head from the piston rod.

Kubota LA340 loader - Attachment and detachment

Auto lock attachment and detachment

The side frame is mounted on the main frame. The side frame can be locked or freed by controlling the mounting lever on the lever guide. When the bucket is lifted up, the side frame and the main frame are locked. When the front wheels are lifted up by lowering the bucket to the ground, the operator can control the mounting lever easily and release the hook mounted on the main frame by hand. Function of auto lock attachment and detachment - When the mounting lever is moved to the upper position of the lever guide, the hook is unlocked from the main frame. As a result, the side frame can be disconnected from the main frame. When the mounting lever is moved to the lower position of the lever guide, the hook is locked to the main frame. As a result, the side frame is locked to the main frame.

Mechanical loader frame standing mechanism

The LA340 loader stand is fixed to the loader arm by the stand hooks. These stand hooks can be controlled by moving the stand lever. The stand rod is connecting the stand lever and the stand hooks. When the stand lever is moved downward, the stand hooks are pulled in and free the loader stand from the loader arm.

Removing attachments

Lower the attachment to ground level with the attachment slightly in the rolled back position. Stop the engine and set the parking brake. Pull the quick attach coupler handles to the unlatched position to release the latching pins. While sitting in the operator's seat of Kubota BX23, BX23S tractor, start the engine and slowly move the loader control lever to the dump position until the attachment is pushed away slightly from the quick attach coupler. Lower the boom of the loader so that the quick attach coupler mounting plate clears the attachment saddle. Back away from the attachment slowly. If an attachment is not going to be attached to the quick attach coupler immediately, push the quick attach coupler handles to the locked position to prevent damage to the handle assembly.

Adjusting height of Kubota LA340 loader stand

Make sure that the stand lever is at its low position. Raise the boom until the bucket fulcrum pin comes up to the height of the boom fulcrum pin. Roll back the bucket to maximum. Stop the engine. Apply the adjusting bolts to the right and left stand adjusting blocks. Move the hydraulic control lever to the dump position, and check to see if the stands are folded as specified. Fasten the seat belt, and start the engine. Move the hydraulic control lever to the dump position until the hydraulic pressure gets relieved. Lower the boom to put the bucket on the ground. Lift the stand on the right side of the loader up to the position shown in the following figure. Reposition the adjusting bolt until it touches the stand. Adjust the adjusting bolt in the same way as for the stand on the left side of the loader. Turn the adjusting bolt on the right side of the loader to set the stand pin. Adjusting range ± 15 mm. Lock the stand pin using the lock nut.

Turn the adjusting bolt and lock the stand pin on the left side of the Kubota LA340 loader in the same way as for the right side. Look at the right and left stands to make sure that the heads of the adjusting bolts are pressed upon the stands. Be sure that the stands are parallel with the loader pipe. Slide the stand lever in the upward direction and make sure that the stand gets locked. Set the stand lever to the low position. Fasten the seat belt. Get the engine started, roll back the bucket and move up the boom, both to maximum. Stop the engine. Move the hydraulic control lever to the dump position until the bucket comes to a complete stop. Make sure that the stands are folded as specified. Fasten the seat belt. Get the engine started and raise the engine speed up to the following speed. Engine speed - 1800 rpm. Slowly dump the bucket until the stand touches the boom. Slide the stand lever upward direction, and then slide the stand lever left side completely. Hold the stand by stand hook.

Removing Kubota LA340 loader

Set the engine speed to the following speed, and then raise the boom until the bucket pin is the height of the boom fulcrum pin. Engine speed - 1800 rpm. Dump the bucket fully. Slide the stand lever downward direction completely, and release the stand from the stand hook. Roll the bucket back until its bottom is set at the following angle with respect to the ground surface. Lower the boom and raise the front wheels slightly. Slide the mounting levers of both sides to the upward direction as shown in the following figure. Slowly move the hydraulic control lever to the rollback position to raise the side frames of the loader up and out of the receivers of the main frames. Down the mounting leversof both sides.

Back Kubota BX23, BX23S tractor so that the quick coupler is set at the back of side frame. Stop the engine, and slowly release all hydraulic pressure by moving the hydraulic control lever in all directions. Unfasten the seat belt, and then turn the safety lock button counter-clockwise to unlock it. Raise the lever until it stops. When the third function kit is mounted, remove the connector. Connect the caps to the connectors of mobile side and tractor side. Put the mobile part on the coupler stay. Put the mobile part on the coupler stay for cab model. Place the protective caps and plugs on the ends of the quick coupler. Fasten the seat belt and slowly back the tractor away from the loader.

Installing Kubota LA340 loader

Slowly drive Kubota BX23, BX23S tractor between the side frames of LA340 loader until the rear portion of both side frames touches the main frames. Stop the engine and unfasten the seat belt. Remove the protective caps. Connect the quick coupler and lower the lever until it stops, and then turn the safety lock button clockwise. When mounting the third function kit, remove the caps from the connectors of mobile side and tractor side. Connect the connectors and the caps. Make sure that the mounting levers of both sides are at their low position. Start the engine and operate at the following speed. Slowly move the hydraulic control lever to the up position until the guide bosses of both side frames touch the main frames. Slowly move the hydraulic control lever to the dump position to lower the side frames into the main frames, and engage the bosses of the main frames to the guide bosses of the side frames.

Slowly move the control lever to the dump position until the bucket tilts down as follows. Angle between bucket bottom and ground - About 20 degrees. Slowly move the hydraulic control lever to the down position to lift the front wheels slightly with the loader until the mount hooks are completely mounted on the main frame. Slowly move the hydraulic control lever to the up position until the cutting edge of the bucket comes up slightly off the ground. Make sure that the right and left mounting levers. Raise the boom until the bucket fulcrum pin comes up to the height of the boom fulcrum pin. Make sure that the stand lever is at its low position. Slowly dump the bucket until the stand touches the boom. Slide the stand lever upward direction, and then slide the stand lever left side completely. Hold the stand by the stand hook.

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