The frame of the car is stamped, riveted, consists of two spars of channel section, variable in length, connected by crossbars
In front, the frame is equipped with a front buffer with two towing forks.
On the rear cross member of the frame of KamAZ-5320, KamAZ-53212 vehicles, a towing device with elastic rubber elements providing double-sided shock absorption is installed.
A rigid towing loop without a rubber shock absorber is installed on the rear cross member of the frame of KamAZ-5410, KamAZ-54112 and KamAZ-55111 vehicles, designed to tow a disabled vehicle for a short distance.
It cannot be used for permanent towing of a trailer.
On KAMAZ-55111, KAMAZ-53229 vehicles, the towing device is installed on the rear cross member of the frame, on KAMAZ-65115 - on a subframe fixed in the rear of the frame.
KAMAZ vehicles of various models and configurations have different frames: long depending on the base; the number and design of the crossbars; reinforcing pads and their design; brackets and their position.
Separate samples of frames are shown in the figure
Spars are made of low-alloyed strip steel 8 mm thick. The maximum section of the spar is 262x80 mm.
Cars have different frame lengths depending on the base. The frame of the KamAZ-53212 car has reinforcing lining of the side members in the area of the fifth cross member.
The brackets of the power unit supports, cabin supports and front suspension are connected to the frame parts with rivets and bolts with nuts.
Hitch of the car consists of a hook, the end of which passes through the holes in the rear cross member of the frame, which has an additional reinforcement.
The end of the hook is inserted into a massive cylindrical body, closed on one side with a protective cap, and on the other with a body cover.
A rubber elastic element (buffer) 4, which softens shock loads when starting a car with a trailer from a stop and when driving on uneven roads, is located between two flanges.
A latch is installed on the axle passing through the hook, locked by pawl 6, which prevents the trailer drawbar from disengaging from the hook.
When assembling the tow hitch, screw nut 2 all the way into the flange without applying additional tightening force.
After that, turning the nut 2, you need to align the slots in it with the hole at the end of the hook, and then install the cotter pin. When the holes are aligned, an axial movement of up to 0.5 mm is allowed.
During the operation of the vehicle, nut 2 cannot be used to regulate the axial movement of the hook, since when screwing the nut on, the axial movement of the hook increases.
In the event of axial movement of the hook after a long operation of the vehicle, the towing device should be disassembled and, if necessary, straighten the flanges and replace worn parts.
When the rubber buffer shrinks, it is necessary to install additional ring gaskets between the flanges and the rubber buffer, then tighten the nut, cotter it and put the protective cap 1 in place.
In order to hitch a tractor with a trailer, you need:
- - brake the trailer with the parking brake system;
- - open the tow hook lock;
- - set the trailer drawbar so that the towing eye is at the level of the vehicle's tow hook;
- - carefully move the car back until the tow hook stops in the trailer hitch;
- - throw the towing eyelet over the tow hook and close the lock;
- - insert the trailer plug into the car socket;
- - connect the hose heads of the trailer's pneumatic system to the corresponding heads of the car's pneumatic system;
- - connect the trailer to the car with a safety cable or chain;
- - open the release valves of the pneumatic drive of the trailer brake systems installed on the vehicle (single-wire or two-wire circuit);
- - release the trailer with the parking brake system.
To improve maneuverability when towing a trailer, remove the rear buffers from the vehicle.
During daily maintenance, you should check the condition of the traction govo-coupling device. Pay special attention to the presence of the latch cotter pin.
On service 2:
- - check the free axial travel of the towing device hook, which should not exceed 6.5 mm;
- - use two grease fittings to lubricate the stem and the nut of the tow hitch hook;
- - tighten the nuts of the bolts of the fuel tank brackets.
When service C:
- - check the state of the frame by external inspection. The presence of cracks, traces of corrosion on the shelves of the spars and cross members is not allowed;
- - check the presence of all rivets, in case of absence - install a bolt with a nut.
Main frame defects:
- - curvature of spars and cross members;
- - cracks in the spars along the holes for rivets for fastening the brackets of the rear engine mount (Fig (a));
- - cracks along the holes for rivets fastening to the side member of the cross member bracket No. 3 (Fig (b));
- - cracks in the rear cross member along the holes for the bolts for fastening the towing device (Fig (c));
- - fatigue cracks;
- - weakening of rivet joints;
- - frame geometry violation
Editing the frame, spars and cross members
Deflections and distortions of the frame are determined by external inspection, as well as with the help of a ruler, a probe and various templates made in the form of a square according to the frame design
It is necessary to edit the frame in a cold state with hydraulic jacks or clamps, as an exception, it is allowed to edit with a sledgehammer using mandrels and supports.
The support must be massive and fit snugly against the surface in the dressing area
If the defect cannot be corrected on the assembled frame, the part is removed and corrected separately
Repair of spars and cross members with cracks
We weld cracks in the following order:
- - places on the frame parts that have cracks and are subject to welding, we clean them from paint, dirt, oil and other contaminants to a metallic sheen;
- - the visible end of the crack is determined using a 4x magnifying glass;
- - we cut the edges for the weld to the depth of the crack and to a length exceeding the length of the crack by at least 20-30 mm on each side.
When a part breaks to the full thickness of the metal, we perform cutting on one side to a depth of ¾ of the metal crack. We drill cut cracks along the edges with a drill with a diameter of 5-6 mm;
Mismatch of the surfaces of the welded edges is allowed no more than 0.5 mm
- - weld the crack. We maintain the shapes and dimensions of the seam in accordance with the requirements of GOST 5264-80. Use electrodes of type E46A GOST 9467-75 coated with UONI 13/45 or 13/55.
In case of a through crack, weld on both sides on a copper lining 1 (picture).
After welding, we clean the seam, the reinforcement of the seam after welding should be 1-1.5 mm, at the place where the reinforcing strip is installed, we clean the seam flush with the base metal
- - harden the heat-affected zones with hardening with a hammer until a small flake appears, cover with soil like FL and GF twice;
- - place a reinforcing overlay on the weld.
Make the reinforcing pad from the metal used for the manufacture of spars, steel 15 GYuT TU 14-1-2366-73 and 22G2TYu TU 14-1-2092-77.
Cut out the overlays from the parts of the rejected frames of KamAZ vehicles. Clean the contours and fit tightly in place
The thickness of the overlays should be equal to the thickness of the repaired part and longer than the crack by 20-30 mm on each side.
In width, the overlay should cover the crack by at least 70-80 mm on each side
Use rectangular (Fig. a), triangular (Fig. b) and diamond-shaped (Fig. c) in the form of overlays
The seams of rectangular reinforcing overlays should be only longitudinal; for triangular and diamond-shaped overlays, apply the seams along the overlay contour, starting from the vertical wall towards the shelves (fig)
Install the trim on the inside of the part being repaired; if this installation is not possible, it is allowed to install the trim on the outside.
When installing a lining on a crack with access to the edge of the part, make it longer than the part by the thickness of the metal.
Installing the overlay on the ta crack extending from the hole to the edge of the part, overlap the edge of the hole by 20-30 mm
After welding, we clean the seam from slag
Repair of rivet joints
Riveted joints are checked by inspection and tapping. We cut loose rivets by hand
When the holes for rivets are worn more than 1 mm from the nominal diameter of the hole, weld on a copper lining and drill to the nominal size
Rivet diameter - 12 mm - nominal hole diameter 13 mm;
Rivet diameter 16 mm - nominal hole diameter 17 mm.
Fit the parts tightly together before riveting. Riveting by riveting is unacceptable. For riveting frames, use rivets with a diameter of 12 and 16 mm
Recommended rivet material - steel 08KP GOST 1050-74
Determine the length of the rivet using the following formula: L = a + 1.5 d (mm), where a is the thickness of the package of parts to be riveted (mm); d – rivet diameter (mm)
Riveting should only be cold
Distortions, cracks and breaks on the edge of rivet heads are not allowed
It is allowed to replace rivets with bolts with self-locking nuts and spring washers.
A tightened bolted connection should ensure that the bolt exits the nut by 2-3 threads of the bolt thread
Requirements for a repaired frame
Longitudinal displacement of spars relative to each other is unacceptable
The difference in cross diagonals (d1 - d2) (fig) between the holes for fastening the rear cross member in the lower flange of the side member and the holes for the rear axle buffer is allowed no more than 3 mm
The size of the frame in width should not deviate from the nominal (rice) in the areas between the crossbars by more than 4 mm, and in the areas where the crossbars are installed - by 2.5 mm
The dimensions between the inner cheeks of the front suspension brackets (fig) should not deviate from the nominal by more than 4 mm
The curvature of the frame parts should not exceed 2 mm over a length of 1 m; for a spar, the total curvature should not exceed 6 mm over the entire length of the spar
Alignment must be ensured in the front suspension brackets (a stepped rolling pin with a diameter of 40 mm must pass through both holes of one of the brackets and a diameter of 39 mm through both holes of the other bracket at the same time).
Welds must be free of cracks, pores, cavities in the directional metal, and undercuts in the base metal.
The fastening joints must ensure a snug fit of the surfaces of the parts to be joined at a radius of at least 1.5 of the diameter of the rivet stem relative to its axis, a 0.1 mm probe should not pass between the connected parts
After repair, cover the frame with FL-type primer.
Tow hitch repair
When repairing the tow hitch, do not use nut 2 to adjust the axial travel of the tow hook, as screwing and unscrewing the nut leads to an increase in the axial travel of the hook.
In the event of an axial movement of the hook, the drawbar must be dismantled and, if necessary, straighten the flanges and replace worn parts.
When shrinkage of the elastic element occurs, install additional ring gaskets between the flanges and the elastic element, tighten the nut 2, cotter it and put the cap 1 in place.
In case of wear of the mouth of the hook to a size of more than 55 mm, replace the hook.
When assembling the device, screw nut 2 all the way into the flange without applying additional torque, then align the slots in the nut with the hole at the end of the tow hook and install the cotter pin
When matching holes, an axial stroke of up to 0.5 mm is allowed.
The surface of the trailer hitch must be flat and smooth.
In case of repairing a worn loop by metal welding, carefully clean the loop to give it a geometrically correct shape, otherwise the loop may jam in the opening of the tow hook and break the opening when the road train is turning.
It is not allowed to use a tow hook with a 48 mm opening with a towing eyelet made of a bar with a diameter of more than 43.9 mm.