7.1.2. Repair of a spring suspension bracket
For elimination of malfunctions, replacements of details and knots subject a suspension bracket to full or partial dismantling.
Removal of springs from the car
Removal of forward and back springs is made practically in the identical sequence. For this purpose it is necessary:
- to weaken an inhaling of nuts of step-ladders;
- to disconnect the lower end of the shock-absorber;
- to lift a jack a forward part of the car for removal of forward springs or back so that springs unloaded;
- to substitute technological supports of the corresponding height under the lifted end of a frame and to lower on them the car;
- to turn off nuts of bolts of fastening of rubber-metal hinges of a spring. To take out bolts. If their renting is complicated, to beat out a copper drift not to spoil a carving;
- to turn off nuts of step-ladders and to remove step-ladders;
- to lift the car a jack so that the forward end of a spring left the arm, and the back end — an earring. To remove a spring.
Dismantling of springs
Before dismantling of a spring to clear of dirt and to define their technical condition. If all details are suitable for further operation, then it is necessary to check an arrow of a deflection of a spring in a free state. For this purpose it is necessary to pull thread or a thin wire between axes of ears and to measure distance from thread to the top surface (at a center bolt) the first radical leaf (fig. 6.4) which has to be:
at low-sheet (2 leaves) forward springs — (147±10) mm;
at low-sheet (3 leaves) back springs — (150±10) mm;
at multisheet (4 leaves) forward springs — (135±5) mm;
at multisheet (5 sheets) back springs — (135±5) mm.
The difference of the sizes of an arrow of a deflection of the springs of the same name installed on the car should not exceed 10 mm.
The measurement of an arrow of a deflection of additional springs in a free state needs to be made from the tense thread attached to end faces of the ends of top of a radical leaf to its surface at a center bolt (fig. 6.5).
This size has to be for a one-laminated additional spring (116±5) mm, for three-sheet — (81±5) mm. The difference of these sizes for the left and right additional springs also should not exceed 10 mm.
If as a result of preliminary survey breakages are found, then the spring needs to be sorted in the following order:
- to clamp a spring in a vice in close proximity to a center bolt;
- to turn off nuts of bolts of collars, to take out bolts;
- to turn off a nut of a center bolt and to carefully release a vice as sheets in a strapped spring are in tension.
To wash out kerosene all sheets of a spring, to wipe and examine whether there are no cracks. To replace the broken sheets and sheets with cracks.
Fig. 6.6. A mandrel for a vypressovka of the rubber-metal hinge from ears of springs. Material: steel 40X, HRC 30—34
In case of a rubber lead over metal fittings in rubber-metal hinges they need to be replaced. For a vypressovka of hinges from an ear of a spring it is necessary to use a mandrel, as shown in fig. 6.6 and 6.7.
The weakened rivets of collars need to be pereklepyvat.
Assembly of springs
For increase in an arrow of a deflection of sheets of a spring their rikhtovka blows of the hammer or a sledge hammer as it leads to bystry breakage is inadmissible. The rikhtovka of sheets by rolling between rollers is allowed.
Fig. 6.8. Mandrels for a press fitting of rubber-metal hinges in an ear of a spring and arms. Material: steel 40X, HRC 30—34
When replacing their rubber-metal hinges it is necessary to grease with liquid soap previously. The press fitting of hinges in an ear of a spring needs to be done by means of mandrels, as shown in fig. 6.8 and 6.9. Then to select the required set of sheets. At multilaminated springs to miss the mark surfaces of sheets with graphitic lubricant. At low-laminated springs between sheets to insert plastic laying.
Assembly of springs needs to be made in the following order:
- to podsobrat sheets in the appropriate order and to insert into an opening under a center bolt a technological core diameter equal to diameter of a center bolt;
- in a vice to squeeze the central part of a spring as it is possible closer to a core and to take out it;
- to insert instead of a core a center bolt a head down and to tighten a nut;
- to insert bolts of collars and to tighten them nuts at multisheet and to bend collars at low-laminated springs;
- to release a spring from a vice and to wipe it from excess lubricant;
- to check a spring deflection arrow in a free state as it was specified earlier;
- to suspend a spring vertically and to paint it in black color.
Installation of springs on the car
Fig. 6.10. Device for installation of springs: 1 — a spring; 2 — a jack; 3 — a beam; 4 — step-ladders; 5 — a finger; 6 — a latch
At installation shorter end of a spring has to be turned forward. The inhaling of nuts of their bolts should be made for the correct operation of rubber-metal hinges at the straightened springs. This operation can be executed adaptation (fig. 6.10) by means of a regular jack.
Installation of a spring on the car should be made in the following order:
- to lower the car so that the forward end of a spring entered the arm, and back — in the lower end of earrings;
- on a bolt of the forward end of a spring to establish two conic and one flat washers;
- the bolt subcollected to establish thus in a forward arm and to screw on it a nut;
- to insert a bolt into earrings and a back ear of a spring, to put on a lock washer and to screw a nut on a bolt;
- to straighten a spring by means of adaptation (fig. 6.10), to tighten nuts of bolts of hinges the moment of 120 — 150 N · m (12 — 15 kgfs · l) and to remove adaptation;
- on a forward spring, and also on a back spring of buses from above to put a slip, and on it step-ladders which carving ends to insert into beam openings, then to fix step-ladders by nuts with lock washers;
- on a back spring if it low-sheet, it is necessary to establish an additional spring and a slip;
- if a spring multisheet, then it is necessary to establish on it laying, then an additional spring and on it a slip. Then on a slip and in openings of a pillow of the back bridge establish step-ladders. On carving parts of step-ladders establish lock washers and screw nuts;
- if on the car wheels are established, then it is necessary to remove supports and a jack;
- to tighten finally nuts of step-ladders the moment of 120 — 150 N · m (12 — 15 kgfs · l);
- to attach the lower end of the shock-absorber.