Front and rear shock absorbers
1 - lower eye; 2 – compression valve body; 3 - compression valve disks; 4 - throttle disk of the compression valve; 5 - compression valve spring; 6 - clip of the compression valve; 7 - compression valve plate; 8 - return valve nut; 9 – recoil valve spring; 10 - shock absorber piston; 11 - recoil valve plate; 12 - recoil valve disks; 13 – piston ring; 14 - nut washer recoil valve; 15 - throttle disc of the recoil valve; 16 - bypass valve plate; 17 - bypass valve spring; 18 - restrictive plate; 19 - tank; 20 - stock; 21 - cylinder; 22 - casing; 23 - rod guide sleeve; 24 - sealing ring of the tank; 25 - holder of the stuffing box of the rod; 26 - stem gland; 27 - gasket of the protective ring of the rod; 28 - protective ring of the rod; 29 - reservoir nut; 30 - the upper eye of the shock absorber; 31 - nut for fastening the upper end of the front suspension shock absorber; 32 - spring washer; 33 - washer of the shock absorber mounting cushion; 34 - pillows; 35 - spacer sleeve; 36 – a casing of a shock-absorber of a forward suspension bracket; 37 - stock buffer; 38 - rubber-metal hinge
The shock absorbers of the front and rear suspensions differ in size, the method of fastening the upper part and the presence of a recoil buffer 37 at the front shock absorber, which limits the shock absorber travel during recoil. In addition, the front shock absorber has different performance parameters.
The rear shock absorber consists of a tank 19 with an eyelet, a compression valve (pos. 2, 3, 4, 5, 6, 7), working cylinder 21, rod 20 with piston 10 and recoil and bypass valves, and casing 22 with an eye.
The tank 19 is made of a steel pipe, to the lower end of which an eye 1 is welded, and a thread for a nut 29 is cut in the upper part. The body 2 of the compression valve assembly with the valve disks is inserted into the groove of the eye. It is pressed against the groove by the working cylinder 21. The annular space between the tank and the cylinder is filled with liquid. Inside the working cylinder there is a rod 20 with a piston 10. The piston has vertical channels located along two circles. The channels on a small circle are closed from below by disks 12 and 15 of the recoil valve, and on a larger one - from above by a plate 16 of the bypass valve.
The compression valve is located at the bottom of the cylinder. In the valve body 2, a seat is made, to which the disks 3 and 4 are pressed by the spring 5 through the plate 7. The throttle disk 4 has a cutout through which the liquid is throttled at a low piston speed. A cylindrical groove and four vertical channels are made in the lower part of the valve body, and in the holder 7 there are six side holes and one central one, through which the liquid passes from the reservoir to the cylinder and back.
From above, a guide sleeve 23 is installed in the cylinder, which is sealed in the tank with a ring 24, and the rod outlet is sealed with an gland 26 with a clip 25. All parts located in the upper part of the cylinder are pressed with a nut 29, which has four holes on top for a special key.
Rubber-metal hinges 38 are pressed into the eyes of the shock absorbers.
Checking shock absorbers on the stand
Shock Absorber Working Diagram
1 - effort during recoil; 2 - force during compression
To determine the performance of the shock absorber, check its working diagram on the dyno.
Record working diagrams according to the instructions attached to the stand, after performing at least 5 working cycles, at a shock absorber working fluid temperature of 20 + 5°C, a flywheel speed of 1 s-1 (60 min-1) and a stroke length of 80 mm for the front shock absorber and 100 mm for the rear.
The curve of the diagram should be smooth, and at the transition points (from recoil to compression stroke) without sections parallel to the zero line.
Evaluation of results according to the diagram. The resistance of the recoil and compression stroke is determined by the largest coordinates of the corresponding diagrams.
The highest point of the recoil curve at a scale of 47 N (4.8 kgf) 1 mm should be located at a distance A from the zero line, equal to: 21-28 mm for front shock absorbers, 19-26 mm for rear shock absorbers.
The highest point of the compression stroke curve at the same scale should be from the zero line at a distance B equal to: 3.5-6.5 mm for the front shock absorbers; 4.5-7.5 mm - for the rear.
The control values of the ordinates on the diagrams of the front and rear shock absorbers are set for cold shock absorbers at a shock absorber fluid temperature of 20±5°C.
After checking, remove the shock absorber from the stand and, if necessary, sort out and replace damaged parts.
Repeat the test to make sure the shock absorber is working.