Leaf Springs To assure proper spring life, the maintenance and inspection process must include the entire suspension system of springs and chassis parts.
The motoring public has learned that proper maintenance on their vehicles is essential to obtain longer life and economical service in this age of rising equipment and fuel costs. In most normal maintenance checks, the spring suspension system is sorely overlooked, but a minimum of attention to the spring suspension would yield a longer and more reliable suspension system service.
The motoring public has learned that proper maintenance on their vehicles is essential to obtain longer life and economical service in this age of rising equipment and fuel costs. In most normal maintenance checks, the spring suspension system is sorely overlooked, but a minimum of attention to the spring suspension would yield a longer and more reliable suspension system service.
When warriors of old made punctures in each other with sharp rapiers, the swordsmen liked to test the integrity of their rapiers by bending them almost double to make sure the rapiers would not break in actual combat.
It is customary practice, of some Boat Trailer Leaf Spring manufacturers, to test every assembled spring in a "bulldozer". This bends the spring farther than it could ever be bent in actual service before the axle makes metal-to-metal contact with the frame. While this does test the spring, and would reveal any flaws existing in the steel, the real purpose is something else.
By bending the spring farther in the bulldozer; than it would ever go in actual service; this stresses the metal, on the tension side of the leaves, a little beyond the yield point. This "pre-sets" the spring so that it will reduce, settle or sag in actual use, and steering alignments will be better maintained.
It is obviously impractical to "pre-set" coil springs beyond normal operating compression, because the adjacent coils of a helical spring make contact with each other-before the maximum yield point is reached. This would seem to be the reason why coil spring front suspensions frequently settle or sag, during the first five or ten thousand miles of use, and then have to be replaced in order to restore normal steering alignments.
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Bulldozing or Pre-setting a Leaf Spring
Leaf Spring Types
Practically all leaf springs, as now used on cars, buses and trucks are of the semi-elliptic type. Because the semi-elliptic spring has the outstanding advantages of not only acting as a spring, to resiliently support the vehicle, but also serves the important functions of positioning the axles and of cushioning both driving torque and brake reaction, the simple semi-elliptic type has superseded many other kinds of springs, including cantilever; platform, full elliptic, etc. A semi-elliptic spring gives just as easy riding as the same amount of steel, built into a cantilever of full elliptic spring.
It is customary practice, of some Boat Trailer Leaf Spring manufacturers, to test every assembled spring in a "bulldozer". This bends the spring farther than it could ever be bent in actual service before the axle makes metal-to-metal contact with the frame. While this does test the spring, and would reveal any flaws existing in the steel, the real purpose is something else.
By bending the spring farther in the bulldozer; than it would ever go in actual service; this stresses the metal, on the tension side of the leaves, a little beyond the yield point. This "pre-sets" the spring so that it will reduce, settle or sag in actual use, and steering alignments will be better maintained.
It is obviously impractical to "pre-set" coil springs beyond normal operating compression, because the adjacent coils of a helical spring make contact with each other-before the maximum yield point is reached. This would seem to be the reason why coil spring front suspensions frequently settle or sag, during the first five or ten thousand miles of use, and then have to be replaced in order to restore normal steering alignments.
trtip4a.gif - 2103 Bytes
Bulldozing or Pre-setting a Leaf Spring
Leaf Spring Types
Practically all leaf springs, as now used on cars, buses and trucks are of the semi-elliptic type. Because the semi-elliptic spring has the outstanding advantages of not only acting as a spring, to resiliently support the vehicle, but also serves the important functions of positioning the axles and of cushioning both driving torque and brake reaction, the simple semi-elliptic type has superseded many other kinds of springs, including cantilever; platform, full elliptic, etc. A semi-elliptic spring gives just as easy riding as the same amount of steel, built into a cantilever of full elliptic spring.
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Semi-Elliptic Spring
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Full Taper or Parabolic
Semi-Elliptic Spring
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Full Taper or Parabolic
Although not new to the market, the full taper spring is now very popular for suspension systems on light to heavy truck application as well as some passenger car suspensions. The major advantages to this type spring are its superior ride and overall reduction of vehicle weight, which nets greater revenue per load miles.
The full taper spring, although superior in some aspects, is not as forgiving as its counterpart the multi-leaf spring and should therefore be checked on regularly scheduled maintenance periods.
The full taper spring, although superior in some aspects, is not as forgiving as its counterpart the multi-leaf spring and should therefore be checked on regularly scheduled maintenance periods.
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