Mechanics Components
Charles W. Beardsley
Gears
Spur and helical gears. A gear having tooth elements that are straight and parallel
to its axis is known as a spur gear. A spur pair can be used to connect parallel shafts only.
Parallel shafts, however, can also be connected by gears of another type, and a spur gear
can be mated with a gear of a different type.
To prevent jamming as a result of thermal expansion, to aid lubrication, and to
compensate for unavoidable inaccuracies in manufacture, all power-transmitting gears
must have backlash. This means that on the pitch circles of a mating pair, the space
width on the pinion must be slightly greater than the tooth thickness on the gear, and
vice versa. On instrument gears, backlash can be eliminated by using a gear split down
its middle, one half being rot table relative to the other A spring forces the split gear
teeth to occupy the full width of the pinion space.
Helical gears have certain advantages; for example, when connecting parallel shafts
they have a higher load carrying capacity than spur gears with the same tooth numbers
and cut with the same cutter. Because of the overlapping action of the teeth, they are
smoother in action and can operate at higher pitch-line velocities than spur gears. The
pitch-line velocity is the velocity of the pitch circle. Since the teeth are inclined to the
axis of rotation, helical gears create an axial thrust. If used singly, this thrust must be
absorbed in the shaft bearings. The thrust problem can be overcome by cutting two sets
of opposed helical teeth on the same blank. Depending on the method of manufacture,
the gear may be of the continuous-tooth herringbone variety or a double-helical gear
with a space between the two halves to permit the cutting tool to run out. Double-helical
gears are well suited for the efficient transmission of power at high speeds.
Helical gears can also be used to connect nonparallel, non-intersecting shafts at any
angle to one another. Ninety degrees is the commonest angle at which such gears are
used.
Worm and bevel gears. In order to achieve line contact and improve the
load-carrying capacity of the crossed axis helical gears, the gear can be made to curve
partially around the pinion, in somewhat the same way that a nut envelops a screw. The
result would be a cylindrical worm and gear.
Worm gears provide the simplest means of obtaining large ratios in a single pair.
They are usually less efficient than parallel-shaft gears, however, because of an
additional sliding movement along the teeth. Because of their similarity, the efficiency
55
of a worm and gear depends on the same factors as the efficiency of a screw.
Single-thread worms of large diameter have small lead angles and low efficiencies.
Multiple-thread worms have larger lead angles and higher efficiencies.
查理比尔兹利
齿轮
带动和螺旋齿轮。一个齿轮齿后,常常被认为是直与平行
其主轴是众所周知的是一个齿轮等。一种激励,一双可以用来连接平行槽只。
平行槽,不过,也可以连接齿轮的另一种类型,和一个正齿轮
可以交配与齿轮的一种不同类型。
为防止干扰,由于热膨胀,以帮助润滑,并
弥补不可避免的失实之制造,一切权力传递齿轮
必须有反弹。这意味着对球场上界一个交配一双,空间
宽对齿轮必须稍微大于齿厚对齿轮,并
反之亦然。对仪器装备,反弹是可以消除用齿轮分裂下跌
其中,其中一半被腐表相对其他弹簧势力分裂齿轮
牙齿占据全宽的小齿轮的空间。
螺旋齿轮具有一定的优势;举例说,当连接轴平行
他们有较高的承载能力比齿轮具有相同齿数
切与上年刀。由于重叠行动的牙齿,他们是
畅顺行动,并可以操作的音调较高线速度比齿轮。该
漆黑的夜里,线速度,是速度的草地循环。由于牙齿倾向于向
旋转轴,螺旋齿轮创造一个轴向推力。若单用,这个推力必须
沉醉于轴轴承。推力问题,是可以克服的,由切割两套
反对的螺旋齿就同一空白。根据制造方法,
齿轮可能会持续齿鱼骨型品种或双螺旋齿轮
同一个空间之间的两半,以准许刀具,以一发不可收拾。双螺旋
齿轮非常适合高效率传输功率高速。
螺旋齿轮也可以被用来连接非平行,不相交的竖井任何
角度对另外一个人。 90度,是最常见的角度,在这种齿轮
用。
蜗杆与锥齿轮。为了实现线接触和改善
承载能力的交叉轴螺旋齿轮,齿轮,可向曲线
部分周围的小齿轮,在一定以同样的方式一个螺母信封螺丝钉。该
结果将是一个圆柱蜗杆和齿轮。
蜗杆齿轮客户提供最简单的方式获得大比率,在一个单一的一双。
他们通常效率较低,比平行轴齿轮,不过,由于一个
额外滑运动,沿牙齿。由于其相似性,效率
55
一蜗杆和齿轮取决于同样的因素,因为效率的螺丝钉。
单一线程蠕虫的大直径有小铅角度和低效率等。
多线程的蠕虫有较大的铅角度和更高的效率
悬赏分:10 - 离问题结束还有 14 天 23 小时
Mechanics Components
Charles W. Beardsley
Gears
Spur and helical gears. A gear having tooth elements that are straight and parallel
to its axis is known as a spur gear. A spur pair can be used to connect parallel shafts only.
Parallel shafts, however, can also be connected by gears of another type, and a spur gear
can be mated with a gear of a different type.
To prevent jamming as a result of thermal expansion, to aid lubrication, and to
compensate for unavoidable inaccuracies in manufacture, all power-transmitting gears
must have backlash. This means that on the pitch circles of a mating pair, the space
width on the pinion must be slightly greater than the tooth thickness on the gear, and
vice versa. On instrument gears, backlash can be eliminated by using a gear split down
its middle, one half being rot table relative to the other A spring forces the split gear
teeth to occupy the full width of the pinion space.
Helical gears have certain advantages; for example, when connecting parallel shafts
they have a higher load carrying capacity than spur gears with the same tooth numbers
and cut with the same cutter. Because of the overlapping action of the teeth, they are
smoother in action and can operate at higher pitch-line velocities than spur gears. The
pitch-line velocity is the velocity of the pitch circle. Since the teeth are inclined to the
axis of rotation, helical gears create an axial thrust. If used singly, this thrust must be
absorbed in the shaft bearings. The thrust problem can be overcome by cutting two sets
of opposed helical teeth on the same blank. Depending on the method of manufacture,
the gear may be of the continuous-tooth herringbone variety or a double-helical gear
with a space between the two halves to permit the cutting tool to run out. Double-helical
gears are well suited for the efficient transmission of power at high speeds.
Helical gears can also be used to connect nonparallel, non-intersecting shafts at any
angle to one another. Ninety degrees is the commonest angle at which such gears are
used.
Worm and bevel gears. In order to achieve line contact and improve the
load-carrying capacity of the crossed axis helical gears, the gear can be made to curve
partially around the pinion, in somewhat the same way that a nut envelops a screw. The
result would be a cylindrical worm and gear.
Worm gears provide the simplest means of obtaining large ratios in a single pair.
They are usually less efficient than parallel-shaft gears, however, because of an
additional sliding movement along the teeth. Because of their similarity, the efficiency
55
of a worm and gear depends on the same factors as the efficiency of a screw.
Single-thread worms of large diameter have small lead angles and low efficiencies.
Multiple-thread