The Silvatech Linear Positioner Set Controller controls a hydraulic cylinder on each headblock to make sets and position the knees. It provides the ease of operation and unmatched assistance for the sawyer for which Silvatech has become well known. This system also offers outstanding accuracy, speed, and tapering capability at a price the average mill can afford.

The set drive on a conventional carriage consists of a drive motor, gear reducer, brake, chain drive to the set shaft, and either chains or racks and pinions to the knees. These mechanical drive components introduce some inherent variation in stopping distance and therefore some degree of inaccuracy. Knee speed is limited to a level at which stopping distance is reasonably predictable; the higher the speed, the larger the stopping distance and the more variation. Knee alignment must be maintained by The Silvatech Linear Positioner Set Controller solves each of these problems making the sawing process faster and more precise than previously possible.

SIMPLICITY

Each knee is positioned by its own hydraulic cylinder. The cylinder is fitted with an internal probe to precisely measure the knee's position. The cylinder is mounted via a trunion mount to the back of the bunk with the rod attached to the knee. The motor, gear box, brake, chain drive to the set shaft, racks/pinions or knee chains and taper cylinders are thus eliminated. With them go the major causes of inaccuracy and constant carriage adjustment and maintenance. A linear carriage is obviously a much simpler machine to maintain and with which to produce precisely sized lumber.

SPEED AND ACCURACY

The computer controls the cylinder with a variable flow "servo" valve which controls the flow of oil to the cylinder. This valve allows the computer to ramp the speed of knee travel up and down, providing fast travel and maintaining knee alignment during a move, and slowing it down as the target is approached for extremely precise positioning.

Maximum knee speed can be above 20 inches per second but is normally set at around 12 inches per second. The knee speed will vary depending on the length of the desired move. This means that all sets will be faster than with an ordinary set drive and a 10/4 set will take the same length of time (less than 1/2 second) as required for a 4/4 set, improving sawing rhythm.

TAPERING

One of the biggest advantages to be gained with our linear positioner system is the ability to infinitely taper each log quickly. Most mills sacrifice a great deal of volume and grade recovery by not tapering each log to the best position. (see "The Importance of Setting Tapers Properly" under Sawing Tips)

Some logs will yield the best dollar recovery by splitting the taper and sawing each face parallel to the log center. On other logs, sawing the best faces to full taper (keeping the outside face parallel to the sawline) and removing the taper on the poorer faces will significantly increase dollar recovery. Still others yield the most value by sawing the faces with defects (depending on their number and location) to full taper. The extra length and width of boards sawn in this manner can give you the surface measure and hence the extra cuttingss you need to immprove.

A carriage with taper increments of one or two inches makes it very difficult to taper correctly. The log usually ends up tapered either too much or not enough. Even when you can get it right, you've spent a considerable amount of time since the tapers must be set before the dogs are closed. With the Linear Positioner Set Controller tapering is performed with a rocker switch on the feed or turner handle. Pressing one side of the rocker causes the log to pivot - around the center knee on a three block carriage and around the second or third knee on a four block carriage. Tapering can be performed either before or after dogging and can be accomplished much more quickly and accurately than on a normal carriage. Your sawyer can split the taper or full taper to saw parallel to the outside of the log to maximize grader and put the log closer to where it should be. This infinite skew taper also makes it easier to achieve the desired opening face width. Individual knee tapers can also be provided so that the knee alignment can be made to conform to an odd shaped log. After individual tapering,the relationship of the kness will be maintianed through sets and further tapering. Knees can also be "Locked Out" when not needed. A locked out knee will move to the back of the carriage and remain there until the lock out is cancelled. 

INSTALLATION

The Silvatech Linear Positioner Set Controller for a three or four block carriage includes a computer, switch panel, monitor, a DC power unit to operate the valves, probes for each knee, two probe boxes and cables.

The conversion to linear positioners is reasonably simple on most carriages including most with tong dogs. You'll need a hydraulic power unit (mounted off the carriage), plumbing over the pantogragh, and the cylinders and valves. Silvatech can supply the entire system including the hydraulic system and complete installation. You can also order the system as part of a new carriage installation.

EASE OF OPERATION

The Silvatech linear system is operated just like our Universal Set Controller - the easiest to use and most helpful system on the market. The ease of choosing or changing sets and cants, the scale and product strip showing the sawyer exactly what he has room for on a given face, and the use of fractional rather than decimal displays are all unmatched by competing systems.

The reasons for the development of the original Universal Set Controller were to increase volume and grade yield, production and ease of sawing... in short, to maximize profits. To remain competitive, you need to constantly strive for improvement in these areas. The Silvatech Linear Positioner Set Controller is an affordable solution to many of the obstacles you face in maximizing your profits and maintaining your competitive edge.

 For a more complete document on maximizing your profits please read   How A Linear Positioner Carriage And Scanning System Improves Profits  

Home | Products | Installations | About Silvatech | Sawing Tips | Industry Links | Company News | Contact Us | Site Map