When your machine’s precision motion drive exceeds what can simply and economically be performed via ball screws, rack and pinion is the logical choice. Best of all, our gear rack comes with indexing holes and installation holes pre-bored. Just bolt it to your frame.
If your travel length is more than can be obtained from a single length of rack, no problem. Precision machined ends enable you to butt additional pieces and continue going.
One’s teeth of a helical gear are set at an angle (relative to axis of the gear) and take the shape of a helix. This enables the teeth to mesh steadily, starting as point get in touch with and developing into range contact as engagement progresses. One of the most noticeable advantages of helical gears over spur gears is certainly much less noise, especially at medium- to high-speeds. Also, with helical gears, multiple teeth are usually in mesh, which means less load on every individual tooth. This results in a smoother transition of forces in one tooth to the next, so that vibrations, shock loads, and wear are reduced.
But the inclined angle of one’s teeth also causes sliding contact between your teeth, which generates axial forces and heat, decreasing effectiveness. These axial forces enjoy a significant role in bearing selection for helical gears. Because the bearings have to endure both radial and axial forces, helical gears require thrust or roller bearings, which are usually Helical Gear Rack larger (and more expensive) than the simple bearings used in combination with spur gears. The axial forces vary compared to the magnitude of the tangent of the helix angle. Although larger helix angles offer higher swiftness and smoother movement, the helix position is typically limited to 45 degrees due to the production of axial forces.
The axial loads produced by helical gears could be countered by using double helical or herringbone gears. These arrangements have the appearance of two helical gears with opposing hands mounted back-to-back, although in reality they are machined from the same gear. (The difference between the two styles is that double helical gears possess a groove in the middle, between the the teeth, whereas herringbone gears usually do not.) This arrangement cancels out the axial forces on each set of teeth, so bigger helix angles can be used. It also eliminates the need for thrust bearings.
Besides smoother movement, higher speed ability, and less noise, another benefit that helical gears provide over spur gears is the ability to be utilized with either parallel or nonparallel (crossed) shafts. Helical gears with parallel shafts need the same helix position, but opposing hands (i.e. right-handed teeth versus. left-handed teeth).
When crossed helical gears are used, they can be of possibly the same or opposite hands. If the gears possess the same hands, the sum of the helix angles should the same the angle between your shafts. The most common exemplory case of this are crossed helical gears with perpendicular (i.e. 90 level) shafts. Both gears possess the same hands, and the sum of their helix angles equals 90 degrees. For configurations with opposing hands, the difference 
between helix angles should equal the angle between the shafts. Crossed helical gears offer flexibility in design, however the contact between the teeth is nearer to point contact than line contact, so they have lower drive features than parallel shaft styles.