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This procedure tells you how to replace the turret piston. Some of the illustrations in the procedure show the machine without the casting or enclosure. This lets you see the steps.

1. Number Plate
2. Turret
3. Piston Assembly
4. O-Ring
5. Turret Housing

Assemble an Air Regulator Tool (Tools Required) with these parts:

• 1 Air Regulator: (P/N 53-0101)
• 3 fittings: (P/N 58-1693)
• 1 reducer fitting: (P/N 58-3665)
• 1 quick connect fitting: (P/N 58-3710)
• 1 fitting coupler: (P/N 58-0577)
• 10 ft. of 1/2" OD Polyurethane Hose (P/N 58-0730)

KIT PN: 93-30-6165, ST PISTON ASSY KIT EXT CNLT TAB DRIVE. QTY: 1

Additional Parts Required:

• 2 Screws 5/16–18 x 2 (P/N 40-1676)
• 3 Screws 5/16–18 x 1.75 (P/N 40-1716)

Remove the (12) 5/16-18 x 1" screws [1] that hold the piston assembly.

Install (2) 5/16–18 x 3" screws [2] into the piston assembly screw holes and the casting.

Disconnect the CLAMP/UNCLAMP switches [1]. Remove the connector bracket.

Put identification labels on the cables and hoses. This helps you install them. Remove these components in this sequence:

1. Clamp and unclamp hoses [2]
   

    Note: On ST-40/45/50/55 machines, these hoses are threaded to hydraulic fittings.

2. Motor cables [3]
3. Disconnect the home switch [4]
4. The motor
   

    Note: Hold the motor while you remove the motor screws [5].

5. Home switch [6]
6. Home switch flag [7]
7. UNCLAMP [8] and CLAMP air fittings (hydraulic fittings on ST-40/45/50/55) [9]

Remove the screws [1] that hold the plate.

Install (3) 5/16-18 x 1.75" screws [2]. Turn each screw clockwise one turn. Do this again and again to push the plate out.

Remove the plate from the turret body. Remove the (3) 5/16-18 x 1.75" screws [2] from the plate.

Remove the (2) gears [3]. Record the location of the gear spacers. The left gear has a small spacer in the rear and large spacer in the front. The right gear has a large spacer in the rear and a small spacer in the front.

Remove the (6) turret gear screws [4]. Remove the turret drive gear [5].

 Warning: Make sure the air regulator is off. Immediate full pressure to the piston can push the piston out of the casting with dangerous force. This is not safe, and will cause damage to the machine.

Install the UNCLAMP air fitting [1]. Attach the air regulator tool to an air source and to the UNCLAMPfitting.

Turn the regulator adjuster to slowly increase the pressure. Turn until the turret assembly moves out [approximately 3/4" (19 mm)].

Disconnect the air regulator tool from the UNCLAMPfitting [1]. Remove the (2) screws [2] from the turret piston assembly. With aid from one more person, remove the piston assembly.

Clean and apply Mobil CM-P to the (2) inner diameters [1] of the piston bore. Make sure the o-ring [2] (57-0232) in the smaller bore is not damaged. Replace the o-ring if it is damaged.

With aid from one more person, install the piston assembly [3] as follows:

1. Carefully align the piston with the bore. Also align the unclamp tube to the hole in the housing. Push in the piston.
2. Install (2) 5/16-18 x 1.75" screws [4] on opposite sides of the piston. Tighten each of the screws one turn. Do this until the piston assembly moves fully in. Then remove the temporary screws [4].
3. Install (12) new 5/16-18 x 1" screws [5] in the piston assembly. Torque the screws in a star pattern. Refer to Haas Fastener Torque Specifications. Use the value for steel.
4. Use (6) new 5/16-18 x 1" screws [7] to install the turret drive gear [6]. Torque the screws [7] in a star pattern. 
5. Install the idler gears [8]. Check to see if the most current idler gear design 20-10365A, is being used. This gear is easily identified by the four machined slots of the faces of the gears where they contact the gear spacers (highlighted in blue below). Replace any idler gear(s) to the new design as required. Before installing the idler gears, apply Mobil CM-P Moly grease to the internal diameter of the idler gear(s) making sure to fill the internal grease cavity (highlighted in red below). Remove any raised areas or burrs on the internal diameter. If abrasives are used to do this, the gear will need to be cleaned thoroughly before they can be assembled.
   
6. Replace the o-rings and seals. Apply grease to the o-rings and seals. Make sure the gears, o-rings, and seals are in position and engaged.
7. Remove the UNCLAMP fitting [10]. Install a new gasket [9]. Push the gasket against the plate. Use grease to hold the gasket in place.
8. With your hands, push the plate fully in. Align the plate to install and torque the eight (8) screws [11]. Torque the (8) screws. Refer to Haas Fastener Torque Specifications. Use the value for steel.
9. Install the piston shaft [12]. Replace the shaft seal.
10. Add 14 fl oz (410 ml) of Mobil SHC 007 to the gearbox.

Cutaway of idler gear 20-10365A. Grease cavities highlighted in red. Four machined slots highlighted in blue

Apply removable thread-locking compound to the piston shaft threads.

 Caution: Make sure you do not use a permanent thread-lock compound.

Install the home switch flag [1] to the piston shaft. Install the home switch [2]. Install the AIR CLAMP[4] AIR UNCLAMP [3] fittings.

 Note: On ST-40/45/50/55 machines, these are hydraulic fittings that thread onto the hoses.

Install the motor. Torque the (4) mounting screws [5]. Refer to Haas Fastener Torque Specifications. Use the value for steel.

Connect the motor cables [6]. Install the bracket [7] for the AIR CLAMP and AIR UNCLAMPconnectors. Connect the switch cables. Connect the home switch [8].

Replace the o-ring [1]. Grease the o-ring and install it in the groove [2] on the turret housing.

Use a hoist and eye bolts [3] to put the turret in the correct position. Align the turret with the dowel pin. Make sure the turret is in the pocket-1 position.

Install the turret screws [4] in a star pattern. Tighten and torque the turret screws. Refer to Haas Fastener Torque Specifications. Use the value for steel.

Put the number plate [5] in position. Make sure the numbers are correctly aligned. Install the number plate screws [6]. Remove the eye bolts [3].

Set the main circuit breaker to the ON position.

Push [POWER ON].

Release [EMERGENCY STOP].