10 11
MAINTENANCE
Trigger
• With tool held in vice, remove Pin 26 using a pin punch*.
• Remove Trigger 25, Pin 22, Roller 23 and Push Wedge 24.
• Gently push on the head of Trigger Rod 20 and remove together with 'O' Rings 7 and 21, Guide 19, Lip
Seal 18 and Plug 17.
• Assembly is in reverse order to dismantling. Ensure lip of Lip Seal 18 is towards head of tool.
Differential Valve
• Using special flat spanner* unscrew valve locking plug 27, withdraw and remove Spring 104 and ‘0’
Ring 29.
• Using a spanner* remove Silencer 34 and nylon Washer 33 .
• Push Valve Piston 28 out from its housing together with ‘0’ Rings 30, 31 and 32.
• Check Spring 104 for distortion and renew if required.
• Assemble in reverse order of dismantling.
Head Assembly
• Remove Nose equipment prior to commencing dismantling.
• Using spanners* remove Spindle 44 and Locknut 45.
• Remove return spring locknut 46 using a spanner*.
• Remove return spring 47, washer 99 and locking ring 102.
• Check return spring 47 for distortion and renew if required.
• Assemble in reverse order of dismantling.
Rear Casing
• Using an Allen key* remove Screws 40 from stroke set finger 88 and lift off bridge washer 95.
• Disengage stroke set finger 88 by pushing it back against spring 89.
• Unscrew rear casing 86.
• Remove rear casing rubber band 87 if necessary.
• Extract circlip 84 using circlip pliers* and remove sintered silencer 85.
• Complete assembly in reverse order of dismantling.
Distributor
• Using an Allen key* remove two Screws 40.
• Withdraw Distributor 83 together with air motor end plug 81 and ‘O’ rings 82 & 31 taking care not to
drop Ball 79 and push rod 78.
• Using an Allen key* remove four countersunk socket head Screws 58 and withdraw Stroke Stop 57.
• Pull out two Air Supply Tubes 59 and four ‘O’ Rings 60.
• Assemble in reverse order of dismantling.
MAINTENANCE
Hydraulic Piston and Air Motor Assembly
• Wrap adhesive tape around Hydraulic Piston 54 thread and move assembly backwards slowly and firmly.
Using circlip pliers* remove Circlip 52 and Front Seal 51.
• Remove ‘O’ Rings 76 and 77.
• Using two spanners* separate the Hydraulic Piston 54 from Air Motor Casing 75. Shim Adjustment
Ring 55, Movement Pivot 56 and ‘0 Ring 101 will come out with Hydraulic Piston 54.
• Remove air motor assembly out of Air Motor Casing 75, using circlip pliers*remove Circlip 61, then tap
Air Motor Casing 75 on bench to free components.
• Parts 62 to 74 can be pulled out as an assembly, taking care not to drop Pin 74.
• Remove Bearing 62, Planet Gear Spindle 63, three Planets 64, Planet Gear 65 and Spacer 66.
• Using a soft mallet tap splined head of Rotor 70.
• Bearing 67 and Front End Plate 68 will come out with Stator 69 and five Rotor Blades 71. (Rotor 70
remains in place).
• Place Rear End Plate 72 in vice with soft jaws.
• Using a pin punch* tap centre of Rotor 70 to remove Bearing 73. (turn Rotor 70 upside down and Bear-
ing 73 will come out).
• When assembling air motor, rear side of Rotor 70 must just touch Rear End Plate 72 without any axial
gap, (any existing gap will disappear when Bearing 73 is fully located).
• When inserting air motor into Air Motor Casing 75 carefully align parts so that Pin 74 locates in centre
hole between spin on/off ports of air motor casing 75 and Rear End Plate 72.
• When assembling Hydraulic Piston 54 onto air motor assembly, tighten parts by hand and blow air into
one of the outer ports of air Motor Casing 75, checking to see air motor rotates freely.
• When assembling front Seal 51 ensure larger diameter faces rear of tool.
• Complete assemble in reverse order to dismantling.
Item numbers in bold refer to the General Assembly drawing and Parts List (pages 12-13).
* Refers to items included in the 74200-99990 Service kit. For complete list see page 14.
IMPORTANT : Check the tool against daily and weekly servicing.
Priming is ALWAYS necessary after the tool has been dismantled and prior to operating
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