calculating what kind of power i need for rack and pinion 4x8 table

8/13/2019 Calculating What Kind of Power i Need for Rack and Pinion 4x8 Table

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Calculating What kind of power i need for rack and pinion 4x8 table

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eloid:

can someone look this over i think i may have a error here,

Im planing to use dual drive motor on my x axis with rack and pinion set up

5x9 table.

how does that change this calculation...

rack

S1811Y-RB-1P

24 diametrial pitch 20 pressure angele

Pinion gear = 1 in diameterOne rotation = 1 * pi (3.141) = 3.141 in travel per rotation

Target rapid transverse = 1300 ipm

NEMA 34 HIGH TORQUE STEPPER MOTOR 1810 oz-in,

http://www.kelinginc.net/SMotorstock.html

RPM of pinion to achieve rapid transverse = 1300 / 3.141 = 413.88 ~ 414 rpmEstimate stepper RPM = 3000 rpm

Required reduction ratio = 3000 / 414= 7.24:1 ratio

Available peak servo torque = 1810 oz-inTorque output of reduction gearbox = 1810* 7.2 = 13032 oz-in

Torque at radius of pinion gear = 13032/ (7.2 / 2).........................................= 13032/ 3.6 = 3620 N

Acceleration = F = m * a

Available peak force at pinion radius = 3620 N

Estimated mass of gantry = ~150 lbs

3620 = 150 * ?

= 3620 / 150

= 24.133 ipm

Target rapid transverse = 1300ipm

Time to achieve rapid transverse = 1300 / 24.133 = 53.86 sec

how do i calculate my resolution?


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docltf:

looked up the torque and speed for your motor at the keling site.at 1000 rpm motor strength is

1/10 of the rated value.I do not believe you will ever see 3000 rpm.

DAlgie:

I have essentially this machine you have. It will rapid at those speeds, but with motors about halfthe size you have. Note that voltage is your friend when you need power with steppers, mine

runs at 90 volts. Mine has some reduction before the rack, I have never counted teeth on the belt

drive but would estimate it to be 10:1 reduction. I think that you will get what you want withthose huge motors if you have maybe 70 volts feed to them. Apples to apples engineering you

know....

DaveA.

Whacko:

What is the impedance of your motor windings? Low impedance high voltage adaptive drivers

gives you high motor speeds, but you must be carefull not to overheat the motors, as that

destroys the magnetic armature for good. High speed gives huge eddy currents as the current isalso recycled in the off period of the pwm. That translates to temperature rise. I've hammered a

nema 23 motor to beyond its capabilities just for fun. I was impressed. I got close to 3000 rpmwith some reasonable torque, but I must add that it is on a 400V 16A adaptive drive. The current

was limited to 4.65A and the motor was supplied by USDigital. The armature is now

demagnatised, and I now call it a BLDC motor. (Brushless DC motor)

Whacko for destruction ;D

Ian Ralston:Eloid,

You really need a proper maths expert to answer all your questions but I'll have a try and thenthey can shoot me down.

"Pinion gear = 1 in diameter"

Gears operate on their pitch circle diameter (PCD) . A 24DP 1.00 inch OD gear has a PCD of0.917ins.

"Estimate stepper RPM = 3000 rpm"

DAlgie and Docltf are giving you good advice. At 3,000 there is not much torque available. Isthere enough to drive your gantry? 80-90 Volts and a good driver will give usefull torque up to

maybe 2,000 rpm if your slide are low friction you should be OK. Don't be tempted by Whacko's

400V - it only lets out the magic smoke!!

"3620 = 150 * ?

= 3620 / 150

= 24.133 ipm"

You are mixing units here stay with metric or imperial. Acceleration should be in inches/sec/sec

and you can set this in Mach3 so that the stepper does not stall running up to your target speed.


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"Target rapid transverse = 1300ipm"

200 ipm would be more realistic with your steppers. It depends on torque available. Factors thatrob you of torque include - motor detent torque, friction and the inertia of your gantry. If you

want real torque at speed you need servos.

Time to achieve rapid transverse = 1300 / 24.133 = 53.86 sec

Formula you need is v=at . Final velocity = Acceleration X Time applied.

how do i calculate my resolution?

Your resolution will depend on several constants - reduction gearing, how many microsteps from

the driver and is your computer powerfull enough to drive Mach3 at 100kHz kernel speed.Answering these will give you resolution in steps/inch for your table travel.


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We sale variable ratio rack and pinion design since 1999.

Variable ratio rack and pinion set is commonly used for steering systems on automobiles. Rack tooth surface has to

be adjusted in order to achieve variable ratio. Unfortunately, none of existing engineering books provide algorithm

for mathematical calculation of the vr-rack tooth surface. Nether gear generating machines exist for generating vr-

racks. Complicated software is required to calculate tooth geometry on vr-rack. We have information about only five

existing software tool for vr-rack tooth geometry calculation: one from Australia from the original inventor of vr-rack, one from Germany (ZF), and three from General Motors in the US. The currently most advanced and the most

accurate software is the one that we have developed for Saginaw Steering System (former Delphi division of GM) in

2001. From our customers comments we understand that our software produces the most accurate rack tooth form.

The advantage of our software is also capabilities to generate vr-rack tooth forms to mesh correctly with modified

(not involute) pinion. While our software has been used for generating of the traditional vr-racks since 1999 this

article describes advanced options with tooth profile modification that has not been widely used yet, but also

available.

Abstract

Existing variable ratio rack and pinion drives are limited in the amount of variable ratio change along the rack.

Higher gain of the ratio is required for advanced application on racing cars, such as FORMULA ONE, and on

aerospace applications, such as High Lift flight control system or landing gears. The authors have applied DirectDigital Simulation (DDS) method for 3-dimentional modeling of variable ratio rack geometry. Not involute tooth

form has been considered for improving of variable ratio rack. The high resolutions CAD models of different

samples are presented, including Double Novikov, tooth design. The calculation results show advantages of DDS

method for simulation of variable ratio rack geometry with not involute tooth profile. Practical vr-rack simulation

software has been developed.

1. INTRODUCTION

Variable ratio racks (vr-rack) are used in automotive steering systems and in aerospace linear actuators. Figure 1.

Figure 1. 3-dimentional CAD model of vr-rack.

VR-rack has become a common component of an automotive steering system. Variable ratio provides optimized

steering performance by making the steering system less sensitive while driving straight and more sensitive while

making turns. Figure 2.


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Figure 2. Variable ratio gain versus steering angle for a typical steering system.

Vr-racks have been adopted on consumers cars and on racing cars. Formula One racing teams have been taking

advantage of using vr-racks for improved control on high speed and on sharp turns. A racing car normally requires

more sensitive steering system compare to an average consumer car. On a racing car the steering wheel rotates for a

smaller angle in order to provide the same turning effect. Higher sensitivity requirements demand more aggressive

ratio gain on vr-rack. Practically, higher ratio gain is better for a racing car. High ratio gain is also in demand in

aerospace mechanical systems used for secondary flight controls like High Lift systems incorporated flaps on the

trailing edge and slots on the leading edge of a wing. Krueger leading edge actuators can benefit in variable ratio in

particular due to high variation of the load during deployment. Figure 3.


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Figure 3. Variable camber Krueger actuator.

The authors have conducted investigation of non-traditional tooth geometry in comparison with the traditional

involute. Involute tooth form has its limits in providing high ratio gain on demanding automotive and aerospace

applications. It becomes impossible to achieve a conjugated mesh between the involute pinion and vr-rack for high

ratio gain because of increased areas of undercut on the vr-rack tooth. Figure 4.

Figure 4. Unacceptable increase of undercut area on the vr-rack tooth generated by an involute pinion with

high ratio gain.

Modification of the involute tooth profile and use of not involute tooth forms extends flexibility in design of extreme

vr-racks. Figure 5.


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Figure 5. Double Circular (DC) tooth profile.

The existing production methods of vr-racks and pinions are very capable of producing any tooth forms. Practically

the manufacturing process for the vr-rack is the same for involute and for not involute tooth form because the vr-

racks are produced by forging, EDM or single-point milling. Manufacturing of the not involute pinion may be some

more expensive because of slightly higher cost of not involute cutting tools. But in a high production values thehigher cost of the cutters is offset by increasing life of the cutters and reducing requirement for the accuracy of the

finished parts. Modern manufacturing capabilities do not limit the geometry of the vr-rack or the pinion tooth.

However, the existing limitations of the Theory of Gearing [1] do not provide a practical theoretical solution for

manufacturing of vr-racks of different geometry. Direct Digital Simulation (DDS) method [2][3] makes it possible

to create mathematical models of different gears including mathematical model of vr-rack with not traditional tooth

form. Traditional vr-rack software limits designers by involute tooth profile.

DDS method has been applied for digital simulation of tooth generating action on a vr-rack. Unlike the traditional

method, DDS method allows to use arbitrary curve as the generating tooth profile to generate a vr-rack. Practical

software packages have been developed and successfully employed in mass production. Advanced graphical 3-

dimentional graphical user interface has been introduced for the first for vr-rack design, which allowed improvement

of geometry analyses on the design and product development stage of vr-rack. Figure 6.


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Figure 6. Output of 3-dimentional of vr-rack geometry.

DDS vr-rack software-products have been tested in process of design and manufacturing of vr-racks for Formula-I

racing cars, for consumer cars, and for aerospace applications.

2. Advance in Direct Digital Simulation:Direct Digital Simulation (DDS) method has been practically used since 1986 for automotive, aerospace

and marine applications. In 1986 DDS method has been adopted for design and development of Double

Circular (DC) helical gears improvement of power to weight ration on MI-28 helicopter transmission.

Figure 7.

Figure 7. Mi-28 Havoc Attack Helicopter.


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At Mil Helicopter DDS method has been practically adopted for developing of simulation software with

graphical visualization of non-involute tooth contact pattern. Non conforming tooth profiles have been

recognized to have some advantages in performance. However, not they did find many practical

applications due to sensitivity to the center distance Figure 8. Vr-rack is sensitive for center distance even if

the has the traditional involute tooth form. Because of its sensitivity, involute vr-rack looses its single

advantage to a not involute vr-rack. Using the DC tooth geometry on vr-rack can provide the same

advantage as on helicopter gears. More specifically DC gears may provide quieter operation and lover

variation of the backlash.

Figure 8. 3-d visualization of not involute tooth contact used at MIL Helicopter in 1986.

DDS method has proved to be a low cost and effective method for digital simulation of the tooth geometry

and for 3-dimentional tooth contact analyses of complex helicopter gear systems. The main advantage of

DDS versus the traditional method is increased visualization capability that helps to present the gear tooth

contact at high level of details. Figure 9.


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Figure 9. DDS visualization of Novikov tooth contact.

DDS has been used for development of a worm face gear drive. The high level of details that can be

obtained from DDS method had helped to design and propose a low cost alternative to a hypoid drive axle

gear. [4] Figure 10.


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Figure 10. DDS digital model of a worm face gear.

In the United States DDS method has been promoted by ZAKGEAR [5] for automotive, marine and

aerospace application since 1996. ZAKGEAR has developed several custom software packages for

different applications including spiral bevel and hypoid gear simulation software. Figure 11.

Figure 11. Example of 3-dimentional output of DDS spiral bevel and hypoid gear software.

3. Basics of Direct Digital Simulation (DDS):Direct Digital Simulation (DDS) is a straightforward method of modeling, which is based on mathematical

representation of subtracting one object, the tool, out of another, the work part. [5] Figure 12. The key difference

between DDS and the Theory of Gearing is that DDS is not using elements of differential geometry. The underlying


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engineering idea of DDS algorithm is more similar to the methods used in developing of solid modeling CAD

software products. The difference between DDS and the standard CAD product is that DDS has a higher level of

optimization in the algorithms, which are used for simulation of the tool pass.

Figure 12. Graphical presentation of DDS application to spiral bevel gear cutting.

Simplified DDS operations can be performed on standard CAD software like AutoCAD, Unigraphics, orPro/Engineer. Standard CAD software has capability of simplified programming. Below is an example of AutoLISP

program that can be used in AutoCAD for DDS generation of a true spiral bevel or hypoid gear.

(defun G()

(setq dt (* dfi al))

(setq x 0.0)

(getreal "stop")

(setq i 0)

(while (< x pi)

(setq i (+ i 1))

(command "copy" sb "" (list 0 0) (list 0 0))

(command "subtract" gear "" (entlast) "")


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;;; rotate the cutter

(command "rotate" sb "" (list 0 0) (list (cos dt) (sin dt)))

;;; rotate the gear

(command "ucs" "ob" axis)

(command "ucs" "y" 90)

(command "rotate" gear "" (list 0.0 0.0) (list (cos dfi) (sin dfi)))

(command "ucs" "w")

(setq x (+ x dfi))

)

)

While simplified simulations can be done on standard CAD software, advanced DDS algorithms provide critical

features that can not be achieved on standard CAD programs. Recently delivered DDS software is capable of 3-

dimentional simulation of tooth contact, sliding velocities contact pressure and as the result DDS is capable of

accurate simulation of driving efficiency. The main advantage of the method is an optimized mathematical

algorithm for more productive, more accurate and faster calculation. In result, DDS software can offer higher

resolution and more accurate calculation results compare to other software products. Figure 13.

Figure 13. Comparison of ZAKGEAR calculation results versus traditionally used software for spiral bevel

gear tooth contact analyses (TCA).

Because of its high resolution capability DDS method helps making discoveries that could not be done without

DDS. For example, DDS has been used for simulation of extremely high-resolution 3-d-tooth contact of Novikov vr-


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rack. It has been discovered that the form of Novikov tooth contact is different from what it was predicted before.

Figure 14.

Figure 14. DDS high-resolution 3-dimentional calculation of Novikov tooth contact compare to theoretical

prediction based on the traditional theory.

The discovery of the real form of Novikov tooth contact provided a clue how to increase the load capacity of

Novikov gears and on vr-ratio racks with Novikov tooth form. It has been discovered that increasing of the profile

modification of Novikov gear reduces the contact area more than it was predicted by the classic gear theory, which

was traditionally based on the assumption of the contact ellipse. Accurate and high-resolution digital models helped

to find a solution for design improvement of Novikov gears so the valuable contact area will not be lost by the

excessive profile modification. DDS has offered an easy to understand visuals explanation of advantaged of Double

Contact (DC) Novikov tooth form versus traditional single contact form. Figure 15.

Figure 15. DDS model of contact on DC tooth profile. Standard DC profile by Russian GOST standard is

used.

3. Applying Direct Digital Simulation (DDS) for variable ratio vr-rack.


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Using DDS for vr-rack has become critical due to high requirements to accuracy and manufacturability of the vr-

racks. The one of disadvantages of the traditional vr-rack software is failure to simulate the correct form of root

fillet, which is generated by the tip of the generating pinion. Figure 16.

Figure 16. Tip of the generating pinion produces an undercut fillet area at the root of the vr-rack tooth.

While the classic gear theory provides a formulated solution for a simple undercut curvature, it fails in comparison

with DDS if the generation curvature gets more complex than a simple circle. DDS is capable to generate the

undercut in 3-dimensinal space for an arbitrary generating surface. DDS software solves the problem of using

complex generating profiles, such as generated fillets on the root and on the tip of the generating pinion. With

traditional methods it is difficult if not impossible to calculate the vr-rack tooth surface if arbitrary pinion tooth

geometry is used.

Because of the limitations of the traditional software the root fillet curve in many practical designs is replaced by a

simple circle. It results in reduction of active tooth profile and increased clearance requirements.

But the more important limitation of the traditional calculation method is its inability to generate vr-rack geometry

using a not involute tooth form. Not involute tooth forms have shown advantages in noise and load capacity. The

traditional design practices limit the opportunity to design high performance and lower cost vr-racks. DDS method is

more capable, more flexible and, it has been proved to design a higher performance steering racks for Formula One

cars. The advantages of DDS method for vr-rack design are:

higher calculation accuracy capability to generate the root area of the rack tooth for different tip forms of the generating pinion capability to calculate vr-rack geometry using not involute tooth profiles for smooth and quiet operation

with higher ratio gain.

The authors have been delivered several DDS software products including software for vr-rack which also includes

capability to simulate the dynamic tooth contact and in result, to analyze driving efficiency for different tooth forms.

It has been found that Double Circular (DC) tooth form provides significantly reduced noise and reduced deflection

of the rack due to lowered, up to 10 degrees or less, pressure angle at the pitch point of the tooth contact. The


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naturally rounded tip and the root of the DC tooth reduce the undercut areas and in addition it improve forging

production process. Figure 17.

Figure 17. Comparison of DC tooth form and involute tooth form for manufacturability by forging.

It has been noticed that use of nonconforming tooth profile makes vr-rack less sensitive for shaft misalignments.

While the contact pattern on DC tooth is still as sensitive to the center distance as for involute tooth, the sensitivity

to skew of the pinion axis has been significantly reduced. As the result, the DC tooth form on variable ratio rack

allows higher deviations in manufacturing process and it provides quieter and smoother operation of the steering

rack and better feel of the steering, which is resulting in added value to the finished product. Reduction of the noise

level is a very important factor for consumers cars especially if to take into account cost reduction of the proces s to

produce vr-racks. Figure 18.

Figure 18. DC vr-ratio rack is more suitable for forging because of round corners and lower requirements for

profile accuracy.

4. Conclusion:


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Direct Digital Simulation (DDS) method has been practically applied for improving and cost reduction of design and

production of variable ratio vr-rack and pinion linear actuators for automotive steering systems and for aerospace

applications. With a help of DDS it has become possible to open new opportunity for design of improved vr-racks

with not involute or modified involute tooth form because, in many applications, not involute tooth form provides

advantages in cost and performance. While not involute tooth form seems to be more complicated in manufacturing

of gears it does not apply to manufacturing of vr-racks. In fact, cost of vr-rack with DC tooth form is reduced by

advantages of more forgeable tooth geometry and lower requirements to accuracy.

6. References1. Litvin F.L. Theory of gearing // USA: NASA, 1989. 2. Lunin S.V. "Direct Digital Simulation for Gears" Proceedings of the JSME International Conference on

Motion and Power Transmissions, MPT2001-Fukuoka, Japan, November 15th - 17th, 2001

3. Goldfarb V.I., Lunin S.V., Trubachev E.S. Direct Digital Simulation for Gears. Vol.1, Izhevsk, IzhSTU,2004, 75p.

4. Lunin S.V.,http://www.zakgear.com/Hypoid_worm.htmlApril 19, 20055.

Lunin S.V., http://www.zakgear.com,July 02, 1999.6. Goldfarb V.I., Lunin S.V., Trubachev E.S. Advanced Computer Modeling Technique in Gear Engineering// ASME IDETC-2003, 9th International Conference "Power Transmissions and Gearing", Chicago, USA,

2003.

3-dimentional CAD model of variable ratio rack and pinion.

Click here to see a sample of VR-rack design.
http://www.zakgear.com/Hypoid_worm.htmlhttp://www.zakgear.com/Hypoid_worm.htmlhttp://www.zakgear.com/Hypoid_worm.htmlhttp://www.zakgear.com/http://www.zakgear.com/http://www.zakgear.com/http://www.zakpro.com/VR_rack.ppshttp://www.zakpro.com/VR_rack.ppshttp://www.zakpro.com/VR_rack.ppshttp://www.zakgear.com/http://www.zakgear.com/Hypoid_worm.html


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TROUBLESHOOTING STEERING SYSTEMS

The most common problems of a steering system are as follows:

Steering wheel play

Hard steeringAbnormal noises when turning the steering wheel

These problems normally point to component wear, lack of lubrication. or an incorrect adjustment.

You must inspect and test the steering system to locate the source of the trouble.

Steering Wheel PlayThe most common of all problems in a steering system is excessive steering wheel play. Steering wheel p

caused by worn ball sockets, worn idler arm, or too much clearance in the steering gearbox. Typically, y

able to turn the steering wheel more than 1 1/ 2 inches without causing the front wheels to move. If the srotates excessively, a serious steering problem exists.

An effective way to check for play in the steering linkage or rack-and-pinion mechanism is by the dry-pafull weight of the vehicle on the front wheels, have someone move the steering wheel from side to side w

the steering system for looseness. Start your inspection at the steering column shaft and work your way t

Ensure that the movement of one component causes an equal amount of movement of the adjoining comp

Watch for ball studs that wiggle in their sockets. With a rack-and-pinion steering system, squeeze the rubthe inner tie rod to detect wear. If the tie rod moves sideways in relation to the rack, the socket is worn an

replaced.

Another way of inspecting the steering system involves moving the steering components and front wheel

the steering wheel locked, raise the vehicle and place it on jack stands. Then force the front wheels right checking for component looseness.

Hard Steering

If hard steering occurs, it is probably due to excessively tight adjustments in the steering gearbox or link

can also be caused by low or uneven tire pressure, abnormal friction in the steering gearbox, in the linkagoints, or improper wheel or frame alignment.

The failure of power steering in a vehicle causes the steering system to revert to straight mechanical oper

much greater steering force to be applied by the operator. When this happens, the power steering gearbox

be checked as outlined in the manufacturer's service manual.

To check the steering system for excessive friction, raise the front of the vehicle and turn the steering wh

steering system components to locate the source of excessive friction. Disconnect the pitman arm. If this

the frictional drag, then the friction is in either the linkage or at the steering knuckles. If the friction is NOwhen the pitman arm is disconnected, then the steering gearbox is probably faulty.

If hard steering is not due to excessive friction in the steering system, the most probable causes are incor

alignment, a misaligned frame, or sagging springs. Excessive tire caster causes hard steering. Wheel alig


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described later in this chapter.

Steering System NoisesSteering systems, when problems exist, can produce abnormal noises (rattles, squeaks, and squeals). Noi

worn components, unlubricated bearingsor ball joints, loose components, slipping belts, low power steer

troubles.

Rattles in the steering linkage may develop if linkage components become loose. Squeaks during turns c

lack of lubrication in thejoints or bearings of the steering linkage. This condition can also produce hard s

Some of the connections between the steering linkage components are connected by ball sockets that canSome ball sockets are permanently lubricated on original assembly. If permanently lubricated ball socket

or excessive friction. they must be replaced.

Belt squeal is a loud screeching sound produced by belt slippage. A slipping power steering belt will usuturning. Turning the steering wheel to the full right or left will increase system pressure and belt squeal. B

eliminated by either adjusting or replacing the belt.


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Tie-Rod Assemblies Two tie-rod assemblies (fig. 8-19) are used to fasten the center linkto the steering knuckles. Ball sockets are used on both ends of the tie-rod assembly. An

adjustment sleeve connects the inner and outer tie rods. These sleeves are tubular in design andthreaded over the inner and outer tie rods. The adjusting sleeves provide a location for toe

adjustment. Clamps and clamp bolts are used to secure the sleeve. Some manufacturers

require the clamps be placed in a certain position in relation to the tie rod top or front surface to

prevent interference with other components. STEERING RATIO One purpose of thesteering mechanism is to provide mechanical advantage. In a machine or mechanical

device, it is the ratio of the output force to the input force applied to it. This means that a

relativety small applied force can produce a much greater force at the other end of the

device. In the steering system, the operator applies a relatively small force to thesteering wheel. This action results in a much larger steering force at the front wheels. For

example, in one steering system, applying 10 pounds to the steering wheel can produce up to 270

pounds at the wheels. This increase in steering force is produced by the steering ratio. Thesteering ratio is a number of degrees that the steering wheel must be turned to pivot the front

wheels 1 degree. The higher the steering ratio (30:1 for example). the easier it is to

steer the vehicle, all other things being equal. However, the higher steering ratio, the more thesteering wheel has to be turned to achieve steering. With a 30:1 steering ratio, the steering wheel

must turn 30 degrees to pivot the front wheels 1 degree. Actual steering ratio varies greatly,

depending on the type of vehicle and type of operation. High steering ratios are often catted

stow steering because the steering wheel has to be turned many degrees to producea small steering effect. Low steering ratios, called fast or quick steering require much less

steering wheel movement to produce the desired steering effect. Steering ratio is

determined by two factorssteering-linkage ratio and the gear ratio in the steeringmechanism. The relative length of the pitman arm and the steering arm determines the steering

linkage ratio. The steering arm is bolted to the steering spindle at one end and connected to the

steering linkage at the other. When the effective lengths of the pitman arm and the steering armare equal, the linkage has a ratio of 1:1. If the pitman arm is shorter or longer than the steering

arm, the ratio is less than or more than 1:1. For example, the pitman arm is about

twice as tong as the steering arm. This means that for every degree the pitman arm swings,

the wheels will pivot about 2 degrees. Therefore, the steering linkage ratio is about 1:2. Most

of the steering ratio is developed in the steering mechanism. The ratio is due to the

angle or pitch of the teeth on the worm gear to the angle or pitch on the sector gear. Steeringratio is also determined somewhat by the effective length and shape of the teeth on the sector

gear. In a rack-and-pinion steering system, the steering ratio is determined largely by thediameter of the pinion gear. The smatter the pinion, the higher the steering ratio.

However, there is a limit to how small the pinion can be made. MANUAL STEERING

SYSTEMS Manual steering is considered to be entirely adequate for smatter vehicles.It is tight. fast, and accurate in maintaining steering control. However, larger and

heavier engines. greater front overhang on larger vehicles, and a trend toward wide tread


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tires have increased the steering effort required. Steering mechanisms with higher gear

ratios were tried, but dependable power steering systems were found to be the answer.

There are several different types of manual steering systems, which are as follows: Worm andsector Worm and rotter Cam and lever Worm and nut Rack and pinion Worm and Sector In

the worm and sector steering gear (fig. 8-20), the pitman arm shaft carries the sector gear

that meshes with the worm gear on the steering gear shaft. Only a sector of gear is used becauseit turns through an arc of approximately 70 degrees. The steering wheel turns the worm onthe lower end of the steering gear shaft, which rotates the sector and the pitman arm through the

use of the shaft. The worm is assembled between tapered rotter bearings that take up the

thrust and toad

calculating what kind of power i need for rack and pinion 4x8 table

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