this patent application is related to co - pending application ser . no . 10 / 209 , 016 titled flat article transport and aligner system , filed currently herewith . the present invention is preferably used to provide a right angle turn prior to an output sorting module at the end of a high speed mail processing inserter system . examples of suitable mail piece sorting modules are described in u . s . pat . nos . 5 , 971 , 161 , 5 , 960 , 963 , 5 , 449 , 159 , 5 , 429 , 249 , 5 , 411 , 250 and 5 , 368 , 287 , assigned to the assignee of the present application , each of which is hereby incorporated by reference . referring to fig1 and 3 components and features of an exemplary embodiment of the present invention may be observed . major modules of the system comprise a ninety degree turn module 1 , a ramp module 2 , a 180 degree transport module 3 , and a sorting module 4 . the turn module 1 , receives envelopes 7 from an upstream module transport 5 . the envelopes 7 are received in a horizontal orientation , with the face of the envelope up , and the flap side of the envelope down . typically , the turn module 1 will be receiving envelopes that have just recently had their flaps closed and moistened for sealing . because the system operates so quickly , it is unlikely that the moistened flap will have had time to dry and a complete seal will not be formed . accordingly , certain features in the preferred embodiment are designed to perform the necessary reorienting and redirecting of the envelope without causing the moistened envelope flaps to pop open and to cause jams . the envelopes 7 are received into turn module 1 via input rollers 10 . from the input rollers 10 , the envelopes are transferred to input nips for a twisted belt pair 11 . twisted belt pairs are transport mechanisms known in the art for transporting and reorienting envelopes from a horizontal to a vertical orientation ( or vice versa ). the twisted belt pair 11 will grip the transported envelopes along a bottom portion of the envelope , so as not to interfere with the flap of the envelope . as the envelopes are transported by the twisted belt pair 11 , a torsion force is applied to change the orientation from horizontal to vertical , and to bring the envelope into an upright position . while traveling in the twisted belt pair 11 , an upper portion of the envelope may receive guiding and support from a horizontal - to - vertical guide 26 . guide 26 may comprise a guide bar or a piece of twisted material that runs parallel the transport path of the twisted belt pair 11 . the guide 26 may serve to assist in keeping the envelope flaps shut during the stress of reorienting the envelope . in order that the twisted belt pair 11 can properly grip the bottom portions of envelopes of varying sizes , the input end of the twisted belt pair may be adjusted in a direction perpendicular to the transport path , as will be discussed in more detail below . at a downstream end of the twisted belt pair 11 , the vertically oriented envelopes enter a turning arrangement . the turning arrangement preferably transports the envelopes in a new direction perpendicular to their original direction . in the preferred embodiment , the transport for the turning arrangement is driven by turn belt 13 . a length of turn belt 13 is positioned such that it is urged against a portion of the circumference of turn wheel 14 , positioned contiguous with the transport path . in the preferred embodiment , turn wheel 14 is an idler roller that is turned by the force of the length of the driven turn belt 13 that is pressed against the portion of its circumference . vertically oriented envelopes received by the turning arrangement are gripped between the turn belt 13 and the turn wheel 14 as it is transported around ninety degrees of the circumference of the turn wheel 14 . turn belt 13 and turn wheel 14 are preferably of approximate equal height , sufficient to grip a lower portion of the envelope between them , preferably between one and two inches high . by gripping just a lower portion of the envelope , turn belt 13 and turn wheel 14 do not place direct bending strain on the envelope flap as the envelope makes the turn . however , the necessary transport force is provided to move the envelopes through the module . as the envelopes make the change of direction in the turning arrangement , the preferred embodiment of the present invention utilizes a turning guide 12 . the turning guide 12 is comprised of a smooth curved surface extending vertically upward along the side of the transport path interior to the turn radius of the transport path formed by belt 13 and wheel 14 . a portion of turning guide 12 disposed above the interface of belt 13 and wheel 14 provides support to for the upper portion of envelopes passing through the turn . such vertical support helps to prevent bending or distortion of the envelopes that might occur while being gripped and turned by the forces acting upon their lower portions . also , the support provided by turn guide 12 keeps the envelope flaps closed to aid in proper sealing . in the preferred embodiment , the radius of the curved portion of the turning guide 12 is just slightly less than the radius of the wheel 14 . in the present invention , wheel 14 , having a relatively low height compared to the envelopes , is more desirable than a taller drum that might be similarly situated for the purpose of providing turning . a first advantage of the wheel 14 over a drum is that the wheel is easier and cheaper to manufacture than a drum , in part because it is smaller and may be composed of less expensive and more easily manufactured parts . another advantage is that the wheel , again being smaller , weighs less and has less inertia . having less inertia , the wheel 14 can start and stop more quickly . the ability to start and stop more quickly provides greater precision in the system , and may allow the system to come to a stop more quickly upon the occurrence of an error condition , like jamming . another advantage of the wheel 14 and turn guide 12 arrangement is that the stationary turn guide can provide a support platform for position sensors 30 to detect the position of envelopes passing within the turning arrangement . if a drum is used , it would be very difficult to arrange a sensor on the moving drum to reliably detect envelopes as they pass through . in the preferred embodiment , shown in fig5 sensors 30 are supported above the belt 13 and wheel 14 on sensor base 27 . one sensor 30 is supported inside the curve of the turning guide 12 , while its corresponding mate is supported oppositely outside of the turning guide 12 . a small hole is provided in turning guide 12 between the pair of sensors 30 so that when an envelope disrupts the optical connection between the sensors , it is known that an envelope has reached that position in the transport path . thus , envelopes are detected as they pass along the surface of turn guide 12 , breaking the path between the position sensors ( preferably optical sensors ). the turn guide 12 and wheel 14 combination allows all of these advantages without any loss of functionality in comparison to an arrangement using a drum . after the envelopes have completed their change of direction in the turning arrangement , they continue to be transported in the vertical position by series of rollers and belts . above the rollers an belts , the envelopes receive support from transport guides 16 and 17 , which continue the guiding function in holding the envelopes upright , and providing support for the envelope flaps . shortly upon leaving the turning arrangement , the envelopes are transferred from turn module 1 to the ramp module 2 . the purpose of ramp module 2 is to raise the envelopes from a lower elevation , at which they were processed earlier in the system , to a higher elevation used by the output sorting module 4 . there is no mechanical requirement that the output sorting process occur at a higher elevation than earlier processing . however , since the sorting includes bins 40 that have a downward slant , and because upstream automated processing generally occurs at a level lower than a comfortable working level for human workers , it is desirable from an ergonomics perspective to raise the envelopes for the output sorting stage . typically the envelopes may be raised by a height of two or three inches . for such elevation changes , the ramp module 2 is preferably inclined at an angle of approximately eight degrees . the input and output portions of the transports for the turn module 1 and the ramp module 2 have particular configurations of rollers and belts to maintain the registration of the bottom of the envelopes substantially parallel to the path of travel , even on the ramp and after the ramp . this is desirable so that envelopes do not become too tilted relative to the travel direction . downstream , such tilting may have the effect of causing jams as the envelopes are processed by the sorting mechanisms . for much of the length of the ramp module 2 the envelope is transported between belts 18 and 19 , with an upper portion of the envelope guided by guides 17 . similarly for an initial linear portion of transport module 3 the envelope is transported between belts 23 and 24 , with an upper portion of the envelope guided by guides 25 . the transport guide pairs 17 and 25 may be comprised of guides that are different heights on the opposite sides of the feed path . in the preferred embodiment , an interior guide 17 or 25 , of a pair is taller , and has a height substantially the same as the turning guide 12 . the taller guide provides support on the flap side of transported envelopes for continued prevention of opening of the flap before a seal can be formed . in transferring envelopes from the turning module 1 to the ramp module 2 , and from the ramp module 2 to the transport module 3 , alignment of the envelopes with the transport path is maintained by specially designed sets of nips comprised of rollers 20 and 21 at the interface of those transports . roller 21 may be a driven roller at the transition end of a transport belt 13 , 18 , 19 , or 23 , as shown in fig1 . roller 21 is driven along with its respective transport belt . opposite roller 21 is idler roller assembly 20 , the preferred embodiment of which is depicted in fig4 . the idler roller assembly is comprised of a toroidal roller wheel 201 rotatably mounted on a shaft 202 mounted on an arm 203 . arm 203 pivots on base shaft 204 . the toroidal wheel 201 is spring biased against roller 21 by the spring 205 providing angular tension between the arm 203 and the base shaft 204 . the toroidal shape of the wheel 201 results in a relatively small point of contact between the toroidal wheel 201 and the driven roller 21 . the small point of contact on the curved outer diameter of the toriodal wheel 201 provides a moving pivot point around which the envelope may turn as the transport direction changes . thus when a forward portion of an envelope driven between roller 21 and idler roller 20 is pulled in a direction with an angular vector different than its current direction , the envelope can pivot at the point between those rollers to adjust to the new vector while it continues to be driven forward with the same forward vector . to reduce frictional forces on envelopes between rollers 20 and 21 even more , in a preferred embodiment , the driven roller 21 may also have a somewhat curved outer surface to further reduce the friction creating surface area of the nip rollers on the envelope . in practice , as an envelope reaches the output of turn module 1 , the first set of nips 20 and 21 at that location are in a horizontal orientation and will continue to drive the envelope in the horizontal direction . however , when the lead edge of the envelope reaches the angled set of second nips 20 and 21 at the beginning of ramp module 2 , then the lead edge of the envelope is urged upward in the angled direction . the envelope pivots upward at both the first and second set of nips as control is transferred to the ramped transport system and belts 18 and 19 . once the envelope comes under the full control of ramp module 2 the envelope has pivoted such that it is angled at substantially the same direction as the ramped transport direction . the same process occurs in reverse as the envelope changes from an angled direction of travel to once again traveling in a horizontal direction at the transition from ramp module 2 to horizontal transport module 3 . if the first set of nips were conventional rollers with flat surfaces , the frictional forces of the nips during a transition to or from ramp module 2 would prevent pivoting . as a result , conflicting vector forces acting on the envelope could cause it to buckle and / or jam . even if slippage in the nips prevents damage to the envelopes , when the envelope comes under the full control of the ramp transport 3 , it will no longer be oriented squarely in the transport direction . this is the situation which is avoided with the preferred embodiment of the present invention . an envelope that is too far askew in the transport cannot be properly processed by sorting module 4 . in a preferred embodiment , an apparatus utilizing the present invention can be adjusted to receive and process envelopes of different sizes . a first location that is sensitive to different envelope sizes is the input rollers 10 at the input to turn module 1 . as discussed previously , the twisted belt pair 11 , and other downstream vertical transport devices grip a lower portion of the envelopes . because the envelopes 7 typically arrive at the turn module 1 with their top edges registered along a common border , variance in the sizes of the envelopes results in different locations for their lower portions relative to the turn module 1 . accordingly , as can be seen in fig1 it is desirable that the input rollers 10 , and the corresponding beginning of the twisted belt pair be adjustable laterally to the transport direction of the envelopes . such adjustment would typically only be necessary when starting a new mail production job using different sized envelopes . as seen in fig1 the input rollers 10 and twisted belt pair 11 are mounted on a base 28 which is laterally movable relative to the frame of the turn module 1 . the lateral position of the base 28 is adjusted by turning adjusting mechanism 15 . in the preferred embodiment , the adjusting mechanism includes a threaded shaft rotatably and fixedly mounted to the frame of turn module 1 . when the adjusting mechanism 15 is turned , a screw interface with base 28 causes the base to move a desired amount to a position where the input roller 10 grip the lower portion of the envelopes at the standard predetermined position . base 28 also preferably supports the turning arrangement comprised of the wheel 14 and turning belt 13 . thus , simultaneously with adjusting the position of input rollers 10 , the same motion can adjust a gap in the transport path between the turn module 1 and ramp module 2 . by making the appropriate adjustment , more space will be provided for larger envelopes to make the transition in the turn upward onto ramp module 2 . to allow a similar adjustment to be made at the transition from the ramp module 2 to transport module 3 , another adjustment mechanism 15 ′ may be provided between those two modules . in an exemplary embodiment , the adjustment mechanism may again be a threaded turnscrew mechanism , with one end fixedly mounted on ramp module 2 and the other end attached though a threaded interface to a movable base in the transport module 3 . in practice , using the preferred embodiment , it has been found that the second adjustment mechanism 15 ′ is not necessary , and that the resulting error in positioning as a result of not adjusting for different envelope sizes is not so great as to affect the downstream sorting process . however for use with different downstream processing , less error may be tolerated , and adjustment mechanism 15 ′ may be necessary . after the envelopes are ( 1 ) reoriented from horizontal to vertical , ( 2 ) redirected by ninety degrees , and ( 3 ) elevated by several inches , the transport module 3 reverses the direction of the transport path by 180 degrees to perform the sorting process in sorting module 4 . sorting module 4 is located to the side of ramp module 2 and transport module 3 that is closer to the inserter system modules upstream of the turn module 1 . in this way an inserter system with an “ l ” or “ u ” shaped footprint can be formed , with the interior of the “ l ” or “ u ” serving as the workspace for operators . workers may attend to upstream modules while being able to observe the operation of the sorting module 4 . also , when it comes time to empty the bins 40 of the stacks of processed mail , the operators may perform that task without having to walk too far from the other stations on the inserter machine . during the sorting process envelopes are transported on the sort transport 41 comprised of a series of belts 42 between which envelopes are transported . at various intervals in the sort transport 41 , deflectors 43 open to deflect the envelopes into the appropriate sort bins 40 . if an envelope cannot be sorted properly into any of the sort bins 40 , whether an error has occurred , or special handling is required , it is deposited into an outsort bin 6 at the end of the sort transport 41 . an outsort guide 44 guides mail pieces into the outsort bin 6 in an orderly fashion . a potential advantage of the preferred embodiment depicted in fig1 is that the outsort bin 6 can be mounted in turn module 1 . as discussed previously , floor space for inserter systems is often at a premium , and the greater the amount of functionality that can be achieved in a shorter distance , the better . the arrangement depicted in fig1 shows that the turn module 1 can provide space for the outsort bin 6 , along the side , and elevated from , the twisted belt pair 11 . by placing the outsort bin 6 at that location , the overall length of the sorting module 4 can be shortened , and greater efficiency is achieved and floor space saved . as an alternative to the arrangement of the modules described above , i . e ., with turn module 1 followed by the ramp module 2 , a different kind of ramp module may precede turn module 1 , and ramp module 2 may be eliminated . in this alternative arrangement , the alternative ramp module is one similar to that depicted as item 10 in fig2 of u . s . pat . no . 5 , 971 , 161 , incorporated by reference . the alternative ramp module raises the envelope in a horizontal orientation using conventional transport techniques . the turn module 1 may then reorient and turn the elevated horizontal envelopes by ninety degrees , as described above . in this alternative embodiment the vertical ramp module 2 after the turn module 1 is not necessary . however , the use of the conventional horizontal envelope ramp may be less desirable for an installation that desires to minimize the length of the system in the first travel direction . the length of the alternative ramp portion will add to the length of the system in the first direction . the preferred embodiment , using ramp module 2 described above , however , may not add any length in any direction as it takes advantage of a length of the sorting module 4 where the system doubles back on itself . although the invention has been described with respect to a preferred embodiment thereof , it will be understood by those skilled in the art that the foregoing and various other changes , omissions and deviations in the form and detail thereof may be made without departing from the spirit and scope of this invention .