Suspension

A suspension is a form of a chord, in the notation Xsus(4|2)y, where X is the name of the chord, 4 or 2 is the subdivision of the suspension, and y is any extra change, for example, 7th chords.

Suspensions are chords composed of the root and the 5th of a chord, plus the 2nd or the 4th, depending on the kind of suspension. 2nds usually resolve to a V first inversion (for example, in D Major, C# E A). 4ths usually resolve to the root (using the previous example, D F# A). Another note: suspensions only very rarely resolve to minor chords, instead preferring major chords.

Suspensions are most commonly used in classical music to add tonal color and emphasis on a cadence in a piece of music, and can sometimes be found tied to the chord that comes after it, called the resolution, with the 3rd sometimes found, in this case, slurred (rhyme for the most part unintended).

In Jazz and modern music, suspensions take on a different role. In Pop and New Age, double-4ths are common (in C, C F Bb), which are just VII chords in first inversion. Another way to visualize this: C D G (the VII, in this case) is equal to D G C (the same chord in first inversion, which became a I 4-4). Anyway.

Jazz uses suspensions that do not resolve traditionally as well, as Major 2nds are not considered entirely dissonant in some styles, allowing musicians greater flexibility and the discovery of new and exciting chords.

SUSPENSION is the part of an automobile (or other wheeled vehicle) which absorbs shock from the road (or other driving surface) by traveling vertically. This is generally performed using a system of lever arms and springs. Various types of auto suspension have various drawbacks and advantages. The original system of a sprung suspension, consisting of a fixed axle mounted on leaf springs, first used in horse-drawn carriages and wagons, is still in use today.

As a vehicle travels forward, it encounters variations in the road. Inertia causes the vehicle to want to continue heading as it has been heading, but the road's surface disagrees. The resulting force, applied to the tires, is translated into upward motion of the suspension. This upward motion is used to compress a spring, storing the energy, and pushing the suspension back down, or pushing the car up. The motion is both damped and limited by a shock absorber, or shock. These devices limit the maximum rate of compression, or closing of the suspension, and rebound, or opening. Without them, vehicles are sluggish during cornering and bounce around or lurch and roll over bumps and through dips.

Some of the more important characteristics of a suspension include travel, or the maximum vertical range of motion; compressing force, or spring rate, shown in foot-pounds or kg/mm; damping, provided by shock absorbers; camber, or the angle at which the wheel meets the ground, leaning sideways; caster, the angle at which the direction of suspension travel meets the ground, fronty to back; and toe, the angle at which a wheel points left or right. Of immense interest is deflection, or the degree of camber or toe change during suspension travel. On various cars, subsets of these things are adjustable. In particular, changing camber and toe is what makes up an alignment job, though all of those things affect handling. camber is one of the most important, because during cornering, where handling matters the most, it can cancel or mitigate the effects of body roll. Finally, the unsprung mass or unsprung weight, the amount of mass which must travel up and down with the wheel. This gives the suspension member inertia which affects the rate at which it recovers from compression.

A suspension in which both wheels on an axle (IE, typically either front or rear) are independent of one another, it is known as an independent suspension. If a fixed axle is used at all, it is most common for the front suspension to be independent and the rear to be a fixed axle, in which there is a literal solid axle between the wheels. This is the typical form for two wheel drive trucks, and just about every American car until the 1980s. However, especially in front wheel drive cars, there has been a drive towards independent rear suspension, or IRS, as it provides superior handling. This is actually cheaper and saves space in front wheel drive cars. It is desirable on all vehicles, however, for its superior handling characteristics.

Independent suspensions generally cost more to produce, but they are functionally better. There are a variety of independent suspension designs out there; The most common are the MacPherson strut suspension, double wishbone, multilink, and torsion beam designs. Double wishbone and multilink are arguably the best, and are used for the vast majority of sports and racing cars. A few cars (F1 and CART types sometimes use a bellcrank suspension in which the shocks are mounted horizontally to save vertical space, for aerodynamics reasons. There are also trailing arm, semi-trailing arm, and Weissach axle designs.

In general, independent suspension allows greater travel and improved handling, but fixed-axle type suspensions are cheaper and stronger. The greatest benefits of independent suspension are improved handling off-road and when the camber of the road changes. Fixed axle vehicles perform well in flat-road or -track scenarios and with hard suspension and sway bars to minimize body roll. However, they do not do particularly well anywhere else.

As far as the springs in suspension, they are generally one of two types; coil, or leaf. Leaf springs are several leaves of flexible metal; The further the vehicle is pressed down (or the suspension is pressed up) the more pieces of metal are bent (in some designs) or the further the bundle is bent; Either way, the resistance rises. You can get bolt-on spring limiters and helper springs to enhance leaf springs. Coil springs can be mounted around a shock or strut, or next to it. Furthermore, they can come as a single or progressive rate spring. Progressive rate springs have multiple rates twisted into them, and so will absorb short bounces without transmitting much force to the chassis. Some suspension systems use charged gas shocks, which actually support some of the load of the vehicle, but in general the entire weight of the vehicle rests upon the springs and the shock absorbers do nothing but damping.^*

There are also active suspension systems. These use some sort of sensors and actuators to actively change some aspect of the suspension, whether it be ride height or damping levels. This is actually used for several purposes. Jeep developed a system that allowed one of their vehicles to literally drive over a foot-tall obstacle. Generally speaking, the sensors used for this type of active suspension are optical and use infrared light, though both sonar and radar can be used (and have been, in prototypes.) The actuators are typically hydraulic.

Another hydraulically-driven active suspension system is the Mercedes automatically leveling suspension. Found even on older vehicles (beginning in the seventies) this system uses a hydraulic valve connected to a lever on the rear sway bar to detect and compensate for excessive squat. As the suspension compresses, the sway bar rotates, thus the linkage moves and changes the valve position. A hydraulic pump attached to the engine runs to the valve in the back, which in turn runs to the rear suspension. This could also be easily done using an air compressor and gas shocks.

Finally, there is a third type of active suspension which lowers the vehicle at higher speeds in order to improve handling. The vehicle rises back up when you are going slower, in order to deal with speed bumps, curbs, and other road hazards.

^* "Shock absorber" is actually a significant misnomer. The springs actually absorb the shock, although some of it is converted to heat when the medium inside the shock absorber (oil or gas) is forced through the narrow apertures that cause it to work. The shock absorbers are actually dampers (like a dash pot) in that they primarily limit the maximum rate of travel. Thus, they cause more shock to be transmitted through the suspension in exchange for preventing your car from constantly rocking and bouncing uncontrollably due to traveling over bumps.

References:

Website: Autozine Technical School (http://www.fortunecity.com/silverstone/lancia/58/technical_school/tech_index.htm)

• Suicide suspension: The most common style of suspension. The body is hung vertically from anywhere between one and six hooks placed across the upper back.



• Chest suspension or O-kee-pa: Generally considered the most painful form of suspension, the body is hung vertically from one or more hooks placed across the chest. This is similar to the Native American rite referred to as "O-kee-pa". Many consider it disrespectful to refer to regular chest suspensions by this name, unless it is accompanied by the full set or rituals and intentions that are used in traditional O-kee-pa rituals. Many people may recognise this ritual from a scene in the movie A Man Called Horse



• Superman suspension: The body is hung horizontally from several (usually ten) hooks placed along the back of the body, creating an effect which looks as if the suspendee is flying.



• Coma suspension: The body is hung horizontally from several (usually ten) hooks placed along the front of the body, so the suspendee hangs face-up.



• Lotus suspension: The body is hung in the yogic "lotus" position, or cross-legged, supported by hooks in the back and legs.



• Tandem suspension: A form of suspension where a second person is suspended from hooks placed in another, already suspended person. In order to minimize cross-contamination, blood bowls are placed on the ropes between the two people, preventing any blood from travelling down the rope and contaminating the person on the bottom.



• Variations: There are several variations to these positions which are accomplished by adjusting the position and number of hooks, or by adding additional ones.

Sus*pen"sion (?), n. [Cf. F. suspension, L. suspensio arched work, imperfect pronunciation. See Suspend.]

1.

The act of suspending, or the state of being suspended; pendency; as, suspension from a hook.

2.

Especially, temporary delay, interruption, or cessation

Of labor, study, pain, etc.

Of decision, determination, judgment, etc.; as, to ask a suspension of judgment or opinion in view of evidence to be produced.

Of the payment of what is due; as, the suspension of a mercantile firm or of a bank.

Of punishment, or sentence of punishment.

Of a person in respect of the exercise of his office, powers, prerogative, etc.; as, the suspension of a student or of a clergyman.

Of the action or execution of law, etc.; as, the suspension of the habeas corpus act.

3.

A conditional withholding, interruption, or delay; as, the suspension of a payment on the performance of a condition.

4.

The state of a solid when its particles are mixed with, but undissolved in, a fluid, and are capable of separation by straining; also, any substance in this state.

5. Rhet.

A keeping of the hearer in doubt and in attentive expectation of what is to follow, or of what is to be the inference or conclusion from the arguments or observations employed.

6. ScotsLaw

A stay or postponement of execution of a sentence condemnatory by means of letters of suspension granted on application to the lord ordinary.

7. Mus.

The prolongation of one or more tones of a chord into the chord which follows, thus producing a momentary discord, suspending the concord which the ear expects. Cf. Retardation.

Pleas in suspension Law, pleas which temporarily abate or suspend a suit. -- Points of suspension Mech., the points, as in the axis or beam of a balance, at which the weights act, or from which they are suspended. -- Suspension bridge, a bridge supported by chains, ropes, or wires, which usually pass over high piers or columns at each end, and are secured in the ground beyond. -- Suspension of arms Mil., a short truce or cessation of operations agreed on by the commanders of contending armies, as for burying the dead, making proposal for surrender or for peace, etc. -- Suspension scale, a scale in which the platform hangs suspended from the weighing apparatus instead of resting upon it.

Syn. -- Delay; interruption; intermission; stop.

© Webster 1913.