Abstract:
A vehicle comprising a chassis, a front axle means and a rear axle means and there being a towing means secured to the rear axle means by which an implement may be towed characterised in that each wheel of the vehicle is provided with a wheel sensor for each wheel, a controller responsive to wheel speed signals from said wheel speed sensors, for sensing skid conditions at said wheels and for generating skid control instructions, a wheel brake for each wheel, responsive to fluid pressure, hereinafter referred to as brake pressure, supplied thereto, from a fluid pressure supply in accordance with a brake demand signal and a skid control device controlled by said skid control instructions for modulating the brake demand signal to provide the brake pressure.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a vehicle, hereinafter referred to as being of the kind specified, including a chassis, a front axle means and a rear axle means suspended from the chassis by rear axle suspension means, and there being a towing means secured to the rear axle means by which an implement may be towed (WO 92/02381).  
           [0002]    In order that a vehicle of the kind specified can operate off road it is conventionally provided with wheels and tyres of relatively large size and usually of the same size on all four wheels.  
           [0003]    For example, the tyres typically fit wheel rims of 24 inch to 44 inch diameter and have tyre width of, for example, 9.5 inches to 1050 mm. Such wheel and tyre combinations are of a relatively high inertia.  
         SUMMARY OF THE INVENTION  
         [0004]    It is desirable that a vehicle of the kind specified may be driven both off and on road at a relatively high speed and an object of the present invention is to facilitate this with enhanced safety.  
           [0005]    According to the present invention we provide a vehicle comprising a chassis, a front axle means and a rear axle means and there being a towing means secured to the rear axle means by which an implement may be towed characterised in that each wheel of the vehicle is provided with a wheel sensor for each wheel, a controller responsive to wheel speed signals from said wheel speed sensors, for sensing skid conditions at said wheels and for generating skid control instructions, a wheel brake for each wheel, responsive to fluid pressure, hereinafter referred to as brake pressure, supplied thereto, from a fluid pressure supply in accordance with a brake demand signal and a skid control device controlled by said skid control instructions for modulating the brake demand signal to provide the brake pressure.  
           [0006]    The skid control device may be controlled by the skid control instructions for controlling the brake pressure in a plurality of cycles each of which comprises a pressure reduction phase and a pressure increase phase and a cycle may also comprise a pressure hold phase between the pressure reduction phase and the pressure increase phase.  
           [0007]    The pressure increase phase may be performed in plurality of steps of pressure increase separated by intervals of constant pressure.  
           [0008]    A skid control device may be provided independently to modulate the brake demand signal for each brake of the rear axle.  
           [0009]    A common skid control device may be provided to supply a common modulated brake demand signal to each brake of the front axle.  
           [0010]    Alternatively, a skid control device may be provided independently to modulate the brake demand signal for each brake of the front axle.  
           [0011]    At least one of the brakes may be a hydraulic brake which is provided with hydraulic brake pressure by a hydraulic/pneumatic actuator which is supplied with pneumatic brake pressure from a skid control device.  
           [0012]    It has been found, surprisingly, and contrary to the opinion of one skilled in the art that a vehicle of the kind specified is able to perform anti-skid braking although it is provided with relatively high inertia wheels and such wheels have been found to respond adequately quickly to the changes in brake regulation demanded by said modulating means.  
           [0013]    The rear axle means may be suspended from the chassis by rear axle suspension means.  
           [0014]    The rear axle means may be suspended from the chassis by a non-reactive suspension.  
           [0015]    The front axle means may be suspended from the chassis by a non-reactive suspension.  
           [0016]    Throughout this specification the term “chassis” is intended to mean both a frame type to which body panels are attached and which carries a vehicle engine and other vehicle components thereon, and a chassis which is of the body shell type in which the vehicle engine and other components are carried.  
           [0017]    By the suspension means being “non-reactive”, we mean that the vertical load on the respective ground wheels and the ground, does not significantly fluctuate in response to changes in the driving torque applied to the ground wheels.  
           [0018]    For example, in one form of non-reactive suspension, the front and/or rear axle suspension means may comprise a pair of links at either side of the vehicle one link of each pair being above the other relative to the ground, the links of each pair being connected at their one ends to the chassis and at their other ends to the or the respective axle means whereby there is no significant change in the vertical loading on the drive wheels in response to changes in the driving torque applied to the ground wheels. Using such a non-reactive suspension, the traction between the ground wheels and the ground, remains high as the vehicle traverses irregularities of the ground, because vertical movement of the axle, in response to irregularities in the ground, is not transmitted to the chassis.  
           [0019]    In another type of non-reactive suspension, one upper link is provided on each side of the vehicle, between the axle and the chassis, and a single lower link is provided between but below said upper links, and a Panhard rod extends transversely to the three links between the axle and the chassis.  
           [0020]    The implement the vehicle is adapted to tow, may be, for example, a plough, harrow, or any other agricultural implement, or a trailer with wheels. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The invention will now be described with reference to the accompanying drawings in which:  
         [0022]    [0022]FIG. 1 is a side illustrative view of a vehicle in accordance with the invention,  
         [0023]    [0023]FIG. 2 is a plan view of the vehicle of FIG. 1, again shown diagrammatically,  
         [0024]    [0024]FIG. 3 is an illustrative perspective view of part of the front end of the vehicle of FIGS. 1 and 2 with various components omitted for clarity,  
         [0025]    [0025]FIG. 4 is an illustrative perspective view of part of the rear end of the vehicle of FIGS. 1 and 2 with various components omitted for clarity, and  
         [0026]    [0026]FIG. 5 is an illustrative perspective view of a three point tractor linkage secured to a rear axle means of the vehicle of FIGS.  1  to  4  with parts omitted for clarity.  
         [0027]    [0027]FIG. 6 is a fragmentary diagrammatic cross section with parts omitted of a front wheel of the vehicle of FIG. 1,  
         [0028]    [0028]FIG. 7 is a fragmentary perspective view of the wheel of FIG. 6,  
         [0029]    [0029]FIG. 8 is a fragmentary view similar to FIG. 6 but of a rear wheel,  
         [0030]    [0030]FIG. 9 is a fragmentary view similar to FIG. 7 of a rear of the vehicle,  
         [0031]    [0031]FIG. 10 is a diagrammatic circuit diagram of a fluid pressure brake system embodying the invention, and  
         [0032]    [0032]FIG. 10 a  is a circuit diagram similar to FIG. 10 but showing a modification. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0033]    Referring to the drawings, a vehicle  10  comprises a frame type of chassis  11  on which an engine  12  is mounted beneath a bonnet  13 , a cab  14  for an operator or driver of the vehicle, and a load platform  15  on which in use, loads may be carried is provided.  
         [0034]    Attached to a front of the chassis  11  is a towing/pushing/lifting assembly  16  which may be of the conventional three point hitch type or any other type of towing hitch assembly as may be desired.  
         [0035]    The hitch assembly  16  is only intended for relatively light work for example in shunting trailers or lifting lighter implements.  
         [0036]    Suspended from the chassis  11  is a front axle  18  which carries a pair of front ground engaging wheels  19   a ,  19   b , one at each end.  
         [0037]    The wheels  19   a    19   b  are mounted on respective hubs  20   a ,  20   b  which are pivotable about axes A, B, respectively in mountings  21   a    21   b  at the respective ends of the front axle  18 , in response to movement of steering rods (not shown) which are connected to a steering box  23  and to the hubs  20   a ,  20   b . The hubs  20   a ,  20   b  may otherwise be interconnected by a further rod (not shown) whereby the wheels  19   a ,  19   b  are pivoted in generally parallel fashion by operation of a steering wheel  24  which is located in cab  14  and controls operation of the steering box  23 .  
         [0038]    Drive may be transmitted to the front wheels  19   a    19   b  from the engine  12  through the axle  18  as is well known in the art.  
         [0039]    The front wheels  19   a    19   b  are each provided with a wheel brake  11   9   a ,  119   b  to be described in more detail hereinafter.  
         [0040]    The front axle  18  is connected to the chassis  11  by means of three links,  25 ,  26  and  27 . Two upper links  25  and  26 , one on each side of the vehicle centre line, and one lower link  27 , on the vehicle centre line. Each of the suspension links  25  to  27  are secured to the chassis  11  at their one ends  25   a - 27   a  by plastic or rubber ball joints, and at their other ends  25   b - 27   b  by farther plastic or rubber ball joints to extension parts of to the front axle  18 , not seen in FIG. 3.  
         [0041]    The two upper links  25  and  26  are generally in a parallel plane to the lower link  27 .  
         [0042]    By virtue of the three suspension links  25  to  27 , and a Panhard rod  22  a non-reactive suspension is provided for the front axle  18  in which changes in vertical loading on the ground wheels  19   a  and  19   b  and hence loss of traction between the wheels  19   a ,  19   b  and the ground  30  is minimised both as the wheels  19   a ,  19   b  and hence the front axle  18  move relative to the chassis  11  as the vehicle  10  is travelling over the ground  30 , and in response to changes in drive torque transmitted to the ground wheels  19   a    19   b.    
         [0043]    Coil springs  31   a ,  31   b  interconnect the front axle  18  and the chassis  11 , the coil springs  31   a ,  31   b  each being of the type which comprise a main coil spring  32  which is relatively yielding at low loads and an auxiliary spring  33  which in this instance comprises a cushion of micro-cellular rubber which is equally stiff for all values of the load so that the coil springs  31   a ,  31   b  become increasingly stiff with increasing load i.e. as the distance between the axle  18  and the chassis  11  at either respective side of the vehicle  10  decreases. A third suspension stage is provided by a rubber spring which supplements the primary coil spring and the secondary micro-cellular rubber spring. If desired gas springs may be used instead of coil springs.  
         [0044]    A pair of shock absorbers  34  of conventional construction are also provided between the chassis  1  land the axle  18  to damp the oscillation of the axle  18 .  
         [0045]    An anti-roll bar  35  is provided, connected to the chassis  11  and the axle means  18 , to provide resistance to movement of either side of the vehicle at the front, about a roll axis  36 , the roll bar  35  being received by first mountings  37  of the axle  18  and second mountings  38  connected rigidly via links  39  to the chassis  11 .  
         [0046]    Suspended from the chassis  11  at the rear of the vehicle is a rear axle  40  which carries a pair of rear ground engaging wheels  41   a    41   b  via two pairs of suspension links  42 ,  43 , and  44 ,  45 , mounted at either side of the vehicle  10  with one link  42 ,  44  of each pair above the other link  43 ,  45  of each pair.  
         [0047]    The one ends  42   a - 45   a  of the links  42 - 45  are connected by plastic or rubber ball joints to the chassis  11  and the other ends  43   b - 45   b  of links  43 ,  45  are also connected via respective plastic or rubber ball joints to extensions to the rear axle  40 . The other ends  42   b ,  44   b  of links  42 ,  44 , are interconnected and coupled to a common point at an extension of axle  40  via a plastic or rubber ball joint to provide a V formation in plan view, with the apex of the V pointing towards the rear end of the vehicle  10 .  
         [0048]    Power may be transmitted to the rear wheels  41   a ,  41   b  from the engine  12  through the axle  40  as is well known in the art. In the present example both the front and the rear wheels are driven from the engine  12  via a differential provided on each axle as is well known in the art.  
         [0049]    The rear wheels  41   a ,  41   b  are each provided with a wheel brake  141   a    141   b  to be described in more detail hereinafter.  
         [0050]    A hydraulic strut  50 ,  51  is provided at either side of the vehicle and the struts  50 ,  51  interconnect the axle  40  to the chassis  11 . The hydraulic struts  50 ,  51 , comprises a piston, connected to the axle  40 , the pistons sliding in and out of cylinders  50   b    51   b  such that as the distance between the chassis  11  axle  40  decreases, hydraulic fluid is ejected from one or both of the actuators  50 ,  51 , depending on which of the ground engaging wheels  41   a ,  41   b  has lifted due to irregularities in the ground  30 .  
         [0051]    However, the struts  50 ,  51 , each incorporate a pair of gas springs  54  each of which contains a diaphragm so that fluid ejected from the cylinders  50   b ,  51   b , acts on one side of the diaphragm, the other sides of the diaphragms being subjected to pneumatic pressure by gas contained within the springs  54 .  
         [0052]    Thus as the wheels  41   a ,  41   b  rise and fall due to e.g. irregularities in the ground, the gas springs  54  provide a cushioning effect. If desired the gas spring spheres may be mounted directly onto the hydraulic struts  50 ,  51 .  
         [0053]    However, the amount of fluid in the cylinders  50   a ,  50   b  is increased and decreased depending on a height regulator means including a linkage  56  which is secured at each side of the vehicle between the link  43  or  45  and the chassis  11 .  
         [0054]    The linkages  56  each comprises a piston and cylinder arrangement, constructed so that as the links  43  for example moves as the load on the axle  40  increases, the respective linkage  56  operates on a valve  57  which allows more hydraulic fluid supplied from a pump (not shown) to be fed into the cylinders  50   b    51   b  to extend the respective piston back to a datum position. Conversely, when the load on axle  40  decreases, the link  43  will move so as to extend linkage  56  which operates valve  57  to allow hydraulic fluid to leave the respective cylinders  50   b ,  51   b  so that the respective pistons are retracted back to a datum position. Hence the amount of hydraulic fluid in the respective cylinders  50   b  and  51   b  will change to extend or retract the pistons, so that the suspension will be self levelling.  
         [0055]    Preferably, a damper means is provided within the valve  57  so that the self levelling function of the suspension does not react to sudden movements of the linkages  43 ,  45 , as the vehicle is travelling, but only reacts, for example 6-10 seconds, after a constant change in payload which causes changes in distance between the chassis  11  and the axle  40  caused as the result of .  
         [0056]    The rear suspension arrangement includes an anti-roll bar  80  which is secured via mountings  81  to the rear axle, and through rigid links  82  to the chassis  11 , the bar  80  providing resistance to the rear end of the vehicle rolling about axis  36 .  
         [0057]    Also attached to the rear axle  40  is a pulling/lifting assembly  60  comprising a three point linkage having a pair of swinging arms  61  pivotally mounted on mountings M 1  of the axle  40 , which arms  61  are each provided with a hook  62  adapted to be engaged with an implement to be pulled. The linkage  60  further comprises a top link  63  also intended to be coupled to an implement to be pulled, the position of attachment of the top link  63  to the axle  40  being adjustable by means of a multi position mounting M 2 .  
         [0058]    The hitch  60  further comprises a pair of control arms  65  which are pivotally mounted on a rocker shaft and headstock casing assembly  66  which is fixed relative to the mounting M 2 . Links  68  extend between the control arms  65  and the outer ends of the swinging arms  61 , and lift cylinders  69  otherwise couple the control arms  65  to the swinging arms  61 .  
         [0059]    The primary purpose of the lift cylinders is to lift the hitch  60  but they also provide damping which is desirable.  
         [0060]    Thus the swinging arms  61  can move up and down relative to the axle  40 , in a controlled, damped manner. The primary purpose at the lift cylinders is to lift, but they do also provide damping which is desirable.  
         [0061]    Lateral stabilisers  70  also connect the axle  40  to the swinging arms  61  to give rigidity or at least controlled float, in a lateral direction.  
         [0062]    In the example shown in FIG. 5, the towing hitch  60  includes a power take off  72  to enable drive to be transmitted to the appropriate machinery being pulled or carried.  
         [0063]    The rear axle  40  suspension is thus also of the non-reactive type by virtue of the four links  42  to  45  and is self levelling by virtue of the hydro-pneumatic springing system used.  
         [0064]    The front wheels  19   a ,  19   b  are carried on hubs  20   a    20   b . Each hub is rotatably mounted by a pair of tapered roller bearings  122  on a stub shaft assembly  123  provided with a pair of trunnions  124  connected to the mountings  21   a ,  21   b  hereinbefore described so as to be pivotable about the pivot axes A, B.  
         [0065]    Drive from the differential of the axle  18  is transmitted via a shaft  125 , a cardan joint  126  and drive shaft  127  which is fastened to the hub  20   a  or  20   b . Although in FIGS. 6 and 7 only the hub assembly at the left hand end of the axle  18  is illustrated it should be appreciated that the hub assembly, drive arrangements and pivot arrangements for steering at the opposite end of the axle  18  are the same and have only the left hand is described in detail herein.  
         [0066]    Connected to the hub  20   a  by a plurality of spaced bolts  128  is a brake disk  128  which is provided with a conventional brake calliper  130  bolted to the hub assembly  123 .  
         [0067]    Fastened to the hub  20   a  is a pole wheel  131  having a plurality of teeth  131   a . A wheel speed sensor  132  is carried by a sensor block  133  which is connected by bolts  134  to the stub shaft assembly  134 .  
         [0068]    Referring now to FIGS. 8 and 9 there is illustrated the left hand end looking forward mounting arrangement for the rear wheel  41   a . Like the front wheel  19   a  it is carried on a hub  140  which is rotatably mounted by a pair of taper roller bearings  141  on a stub shaft assembly  142  which in this case is bolted to the end of the axle  40 . Bolted to the hub  140  is a brake disc  143  which is operatively associated with a brake calliper  144  which is fixed relative to the stub shaft assembly  142 . The hub  140  is rotatably driven by a shaft  145  which extends from one side of the differential disposed in the axle  40 .  
         [0069]    Mounted on the hub  140  is another pole wheel  146  provided with a plurality of teeth  147  around its periphery.  
         [0070]    A wheel speed sensor  148  is carried in a sensor block  149  which is fixed by screws  150  to the stub shaft assembly  142 .  
         [0071]    Referring now to FIG. 10, a braking circuit is illustrated diagrammatically and comprises a pneumatic foot operated valve  160  which is operable by the driver of the vehicle. Air under pressure is fed to the valve  160  via low pressure switches  161  on lines  162  and  163  respectively from air reservoirs  164 ,  165  respectively for the front and rear brakes. Air is supplied to the reservoirs  164 ,  165  from a compressor  166  on a line  167  via an air valve  168  and a circuit protection valve  169 .  
         [0072]    Air in the form of a brake demand signal is supplied from the foot valve  160  towards the front axle  18  on a line  170  and towards the rear axle  40  on a line  171 .  
         [0073]    The air demand signal in the line  170  is fed to a skid control device comprising a solenoid operable pressure modulating valve  172  where the demand signal pressure in the line  170  may be modulated, as hereinafter to be described. The air fed from the valve  172  which may or may not be modulated is a brake pressure.  
         [0074]    The pneumatic brake pressure is fed on the line  173  to an air/hydraulic actuator  174  of conventional type where the brake pressure  173  is converted to a corresponding hydraulic pressure supplied in the line  175  to a connection  176  which supplies hydraulic pressure on line  177  and  178  to the pistons of the callipers  129   a ,  129   b  to provide braking action to the brake discs  128  associated with the left and right front wheels  19   a ,  19   b  respectively.  
         [0075]    The brake demand supplied on the line  171  towards the axle  40  is fed via a first skid control device comprising a first solenoid operated pressure modulating valve  180  and then on line  181  to a further air/hydraulic actuator  182  and the hydraulic pressure corresponding to the brake pressure in the line  181  is fed on line  183  to the brake calliper  144 a to act on the brake disc  143   a.    
         [0076]    The line  171  also extends, via line  184 , to a second skid control device comprising a second solenoid operated pressure modulating valve  185 . The resulting pneumatic brake pressure is fed on a line  186  to a third air/hydraulic actuator  187  from which hydraulic pressure corresponding to the pneumatic brake pressure in the line  186  is fed on a line  188  to a calliper  144   b  to act on a disc  143   a  of the right hand rear wheel.  
         [0077]    The speed of the left and right hand front wheels and of the left and right hand rear wheels are determined by an ECU  190  in response to electrical signals supplied by wheel speed sensors  191 ,  192 ,  193 ,  194  resulting from sensing the passage of teeth T of the pole wheels or sensing rings  130   a ,  130   b ,  146   a ,  146   b . Of course normally no modulation is required by the wheels  172 ,  180  and  185  and the brake demand signal from the foot valve  160  is the same as the pneumatic brake pressure.  
         [0078]    However, when the ECU detects a need to apply brake control then, in accordance with a suitable algorithm well known to those skilled in the art the ECU sends a signal to the skid control devices  172 ,  180 ,  185  as necessary so as to restrain the wheels or wheel of the front and/or rear axle from skidding when the ECU  190  detects that one of the wheels of the front axle or rear axle is slowing towards zero rotation or is stopped.  
         [0079]    Typically the algorithm may cause the skid control device to control the brake pressure in a plurality of cycles each of which comprise a pressure reduction phase and a pressure increase phase and a cycle may also comprise a pressure hold phase between the pressure reduction phase and the pressure increase phase.  
         [0080]    The pressure increase phase may be performed in a plurality of steps of pressure increase operated by intervals of constant pressure.  
         [0081]    In the present example there is shown a 4S/3M system. That is to say a system in which there are four sensors, one for each wheel and three skid control devices or modulators, one modulator  172  supplying a common pressure to the wheels  43   a ,  43   b  on the front axle and two modulators, one for each of the wheels on the rear axle  40 .  
         [0082]    In such an arrangement it is usual for the ECU to control the wheels on the front axle  18  on the basis of the wheel detecting the lowest friction and in this case the amount of braking available from the wheel on the higher friction surface is correspondingly reduced.  
         [0083]    If desired the system may comprise a 4S/4M system in which case not only the rear axle but also the front axle is provided with two modulators  172 ′, one for each wheel, as illustrated in FIG. 10 a . In addition, separate lines  175 ′ and air/hydraulic actuator  174 ′ and connections  176 ′ are provided to feed hydraulic pressure on lines  177 ′ and  178 ′ separately to the wheel brakes  119   a ,  119   b.    
         [0084]    If desired, as illustrated in FIG. 10, air may be supplied from the pressure modulating valves  172  and  185  on lines  192 ,  193  to a further control valve  194  supplied with air on line  196  from reservoir  197  to which air is supplied from the protection valve  169 . Air may also be supplied from the trailer control valve through supply couplings  198 ,  199  to a trailer and a non-return valve  200  and a line  201  to a hand-control valve  202 , to which air is also supplied on line  203  from the trailer control valve  194 . Air is fed, from the hand control valve  202  via a low pressure switch  204  to a parking brake actuator  205 .  
         [0085]    It has been found that the vehicle  10  is well able to travel over a conventional road surface at high speed e.g. at up to 80 kph or more and to brake safely from such speeds without risk of skidding of any of the wheels.  
         [0086]    Because of the relative lightness of the vehicle, it may be necessary to add ballast weights at the front of the vehicle to prevent the vehicle tipping about the axes of rotation of the rear wheels  41   a ,  41   b  when the vehicle  10  is towing a heavy load such as a plough. However, even with such ballast weights fitted, the vehicle will still be considerably lighter than a conventional tractor wherein sufficient traction between the rear drive wheels and the ground is only achieved by increasing the weight of the tractor overall to an undesirable amount.  
         [0087]    Various modifications may be made without departing from the scope of the invention. For example, the chassis  11  shown in the drawings is of the frame type i.e. plurality of body parts  13 ,  14 , the engine  12  and other vehicle components are fitted onto the chassis  11 , whereas the chassis  11  could be body shell type chassis in which the various components of the vehicle are secured.  
         [0088]    Instead of the multi-link type suspension at the front and rear of the vehicle, any other suitable non-reactive type suspension may be provided.  
         [0089]    Particularly for a four wheel drive type of vehicle, it is preferred for the front and rear axle suspension means to be of the non-reactive type. Where only the rear wheels are driven an entirely different front suspension for the front axle, may be provided as desired, even a reactive suspension.  
         [0090]    A vehicle in accordance with a first aspect of the invention need not have the self levelling spring means at the rear of the vehicle as described, but any other non-reactive type of suspension for the rear axle  40  of the vehicle may be provided.  
         [0091]    In the vehicle shown in the drawings, the ground wheels  19   a ,  19   b ,  411   a ,  41   b , are all of approximately the same size. Bigger ground wheels may be provided at the rear of the vehicle if desired.  
         [0092]    In the present example the wheels have a rim diameter of 30″, a tyre width of 480 mm, an aspect ratio R of 70% but the rim diameter may lie in the range 24″mm to 44″, tyre width in the range 9.5 mm to 1050 mm and the aspect ratio in the range 30% min to 100% mm  
         [0093]    In the present specification “comprise” means “includes or consists of” and “comprising” means “including or consisting of”.  
         [0094]    The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.