970945 Volvo.Penta Hexagon screw

1.1 Clutch Proper
This clutch is of a diaphragm spring type in which a diaphragm is employed with the pressure spring. The clutch proper normally transmits power from the engine (clutch lever or clutch pedal released). The diaphragm spring presses, with pivot ring as fulcrum, the pressure plate against the flywheel side by external spring force. The pressed clutch disc revolves together with the flywheel and transmits power to the drive pinion supporting the clutch disc. When the clutch lever is pulled (or the clutch pedal is depressed), the power cylinder is operated from oil pressure from the clutch master cylinder. The clutch release rocker arm in contact with the power cylinder pushes out the clutch shifter with rocker arm pivot as a fulcrum and pushes the finger portion of the diaphragm spring. The diaphragm spring with its finger portion pressed is weakened in external spring force with the pivot ring as a fulcrum and pulls back the pressure plate connected to the clutch cover by the strap plate. For this reason, clearance is produced between clutch disc and flywheel and engine power will not be transmitted.1.2 Clutch Control
When the clutch lever is pulled, hydraulic pressure is produced in the master cylinder, which causes the power cylinder to operate. The action of the power cylinder converts hydraulic pressure into push rod thrust, disengages the clutch and cuts off power transmission. On the other hand, when connected, it provides the clutch with slide and absorbs power transmission impact.Clutch Master Cylinder
(1) Clutch Lever OFF (When Pedal Is Depressed) When the piston is pushed, the return spring whose tension has been acting on the valve seal portion of the valve stem yields and the valve spring causes the connecting port to the oil reservoir tank to be closed. When the piston is further pushed, the hydraulic pressure in the cylinder increases and the fluid is fed under pressure to the power cylinder.(2) Clutch Lever ON (When Pedal Is Released) When the pedal is released, the hydraulic pressure in the power cylinder and the return spring push back the piston. At the same time, the spring seat now pulls the valve stem. As a result, the connecting port to the oil reservoir tank now opens to release hydraulic pressure in the cylinder.Clutch Power Cylinder
The clutch power cylinder connects or disconnects the clutch in converting hydraulic pressure generated in the master cylinder by operation of clutch lever or clutch pedal into push rod thrust.2. Specifications
3. Service Standards
3.1 Service Standard Table
3.2 Tightening Torque Table
4. Special Tool
5. Service Procedure
5.1 Clutch Proper
Removal and Installation
(a) For removal and installation of the transmission, see "Group 22, Transmission".(b) Remove the flexible hose from the clutch power cylinder.(c) Removal of Clutch Cover Assembly While supporting the clutch disc with Clutch Alignment Arbor (special tool), remove the clutch cover assembly. 1. The clutch disc is likely to be deformed. Do not drop it or place parts on it.2. If the clutch disc facing has been contaminated with oil, etc., do not attempt to clean with cleaning oil. If contamination is not serious, wipe with waste cloth.(2) Installation While supporting the clutch disc with Clutch Alinment Arbor (special tool), install the clutch cover assembly. Engage the flywheel knock pins and tighten the bolts to the specified torque. 1. Check and clean the flywheel before installing the clutch. If any abnormality is found, correct or replace.2. Tighten the bolts evenly in a diagonal order.3. Install the clutch disc in the correct direction. The clutch disc must be installed with the side showing the part number facing out.Disassembly, Inspection and Reassembly
Inspection Procedure(1) Facing Wear Measure the depth from the facing surface to rivet head. If the limit has been reached, replace the clutch disc assembly.(2) Clutch Disc Runout Use a runout tester to measure disc runout.If no runout tester is available, place the test arbor on a stool and measure runout of the outer circumference of the clutch disc with a dial gauge. If the limit has been reached, correct or replace.(3) Clutch Cover Assembly Clutch cover, pressure plate, strap plate and diaphragm are rivetted together. If any faults are found, replace the whole clutch cover assembly.(a) Friction surface flatness Apply a straightedge to the friction surface of the pressure plate and insert a thickness gauge to measure flatness.If the limit has been reached, correct by grinding or replace.(b) Pressure plate Replace the pressure plate if its thickness is found to have reached the limit due to friction surface wear.(c) Diaphragm spring Check the diaphragm spring for cracks or damage and replace if defective.Measure wear groove depth of the diaphragm spring finger (portion that pushed the release bearing) and replace if the limit has been reached.(d) Gaps and Looseness Using a thickness gauge, measure the clearance between the diaphragm spring lock pin and pivot ring. If the clearance exceeds the limit, replace.<C2W26-D, C2M26-D> Check the diaphragm spring for excessive play.<C3W28-D>(e) Inspection and adjustment of diaphragm spring installed height * Place Plate (special tool) on a stool and install the clutch cover assembly to the plate.* Install Sleeve and Clutch Alignment Arbor (special tools) and check for uneven diaphragm spring finger height using a thickness gauge. Correct if the limit has been reached.* Adjustment of Diaphragm Spring Use Adjusting Wrench (special tool) to correct uneven height of the diaphragm spring finger.5.2 Clutch Control
Clutch Lever
(1) Disassembly and Inspection (2) ReassemblyFix the stopper bolt at a position where the clutch lever is returned slightly from its fully tilted position. 1. In operating the lever, confirm that it operates smoothly and lock latch is engaged firmly.2. After clutch system piping, operate the lever and confirm that the clutch is disengaged completely.For reassembly, reverse the order of disassembly. Clutch Master Cylinder
(1) Disassembly and Inspection Removal of Piston Assembly Use compressed air from the union to force the piston assembly out of the body.(2) Reassembly Clutch Power Cylinder
(1) Removal and Inst