SYNCHROMESH GEAR BOX

Synchromesh gear box is an automatic means for matching the speeds of engaging dogs. Synchromesh gear box is a device which facilitates the coupling of two shafts rotating at different speeds. Synchromesh unit is used in most of modern gear boxes. In synchromesh gear box, sliding dog clutches are replaced by synchromesh device. The synchromesh devices are used to simplify the operation of changing gear. Synchromesh device helps unskilled drivers to change gears without the occurrence of clashes and damages.

By synchromesh device, the members which ultimately are to be engaged positively are first brought into frictional contact and then when the friction has equalized their speeds, the positive connection is made.

The basic requirements of synchromesh device are:

(1) A braking device such as cone clutch.

(2)  To permit easy meshing means of releasing pressure on the clutch before engagement of gears.

The engine shaft carries a pinion which meshes with a wheel fixed to the layshaft, while the gear on the mainshaft is free to rotate and is permanently meshed with another wheel fixed to the layshaft. Both the pinion and the wheel on the mainshaft have integral dog tooth portions and conical portions. The synchronizing drum is free to slide on splines on the mainshaft. This drum has conical portions to correspond with the conical portions on the gearbox shaft pinion and on the wheel that rotates freely on the mainshaft. The synchronizing drum carries a sliding sleeve. In the neutral position, the sliding sleeve is held in place by the spring loaded balls which rest in the dents in the sliding sleeve (or ring gear). There are usually six of these balls.

In changing gear, the gear lever is brought to the neutral position in the ordinary way, but is immediately pressed in the direction it has to go to engage the required gear. When a shift starts, the spring loaded balls cause the synchronizing drum and sliding sleeve, as an assembly to move toward the selected gear. The first contact is between the synchronizing cones on the selected gear and the drum. This contact brings the two into synchronization. Both rotate at the same speed. When the speeds of the two have become equal, a slightly greater pressure on the gear lever overcomes the resistance of the balls. Further movement of the shift fork forces the sliding sleeve on toward the selected gear. The internal splines on the sliding sleeve i.e. the dog portion, match the external splines on the selected gear the dog teeth are locked up, or engaged, and thus positive connection is established. The gear shift is completed.

CONSTANT MESH GEAR BOX

In constant mesh gear box all the gears are always in mesh and the engagement between the gears which are freely rotating on the transmission main shaft and the transmission main shaft is effected by moving the dog clutches, as explained below.

The engine gear box shaft is integral with a pinion. The pinion meshes with a wheel on the layshaft. The layshaft is therefore driven by the engine shaft. Three more wheels are fixed to the layshaft as in the sliding mesh gearbox. These gears rotate with the layshaft. The transmission main shaft is just above the layshaft and in line with the engine shaft. The three gears (first gear, second gear and reverse gear) on the main shaft are perfectly free to turn on the main shaft. These three gears are in constant mesh with the three wheels on the layshaft. One of these three gears meshes with a wheel on the layshaft through an idler wheel which is mounted and freely rotating on a pin fixed to the gearbox casing. 


The three main shaft gears are, therefore constantly driven by the engine shaft, but at different speeds. The first gear and the second gear rotate in the same direction as the engine shaft while the reverse gear rotates in the opposite direction to the engine shaft.

If anyone of the gears on/the mainshaft is coupled up to the main shaft, then there will be a driving connection between the main shaft and the engine shaft. The coupling is affected by the dog clutch units. The dog clutch members are carried on splined (or squared) portions of the mainshaft. They are free to slide on those squared portions, but have to revolve with the shaft.

If one of the dog clutch members (l) is slid to the left it will couple the wheel (first gear) to the main shaft giving the first gear. The drive is then through the wheels and this dog clutch member. The other dog clutch is meanwhile in its neutral position.

If, with the above dog clutch member in its neutral position, the other dog clutch member (2) is slid to the right, it will couple the wheel (second gear) to the mainshaft and give second gear. If this dog clutch member is slid to the left, it will couple the mainshaft directly to the pinion fixed to the engine shaft. This will give a direct drive, as in the sliding mesh gear box.

The reverse gear is engaged by sliding the dog clutch member (which gives the first gear) to the right. Then it will couple the wheel (reverse gear) to the mainshaft. The drive is then through the wheels, the idler and the dog clutch member.

In the constant mesh gear box, the gears on the mainshaft must be free to revolve. For this, they are either be bushed or be carried on ball or roller or needle bearings.

The main advantages of the constant mesh gear box over the sliding mesh type are as follows:

1. Helical or double helical gear teeth can be used for the gears instead of spur gears. Then gearing is quieter.
2. Synchronizing devices can be used for smooth engagement.
3. Any damage that results from faulty manipulation occurs to the dog clutch teeth and not to the teeth of the gear wheels.
4. Once the dog clutches are engaged, there is no motion between their teeth. But when gear teeth are engaged, the power is transmitted through the sliding action of the teeth of one wheel on those of the other. The teeth have to be suitably shaped to transmit the motion properly.
5. If the teeth on the wheel are damaged, the motion will be imperfect and noise will result.
6.  Damage is less likely to occur to the teeth of the dog clutches, since all the teeth engage at once, whereas in sliding a pair of gears into mesh the engagement is between two or three teeth.

SLIDING MESH GEARBOX

Sliding mesh gearbox is the oldest and simplest form of gear box. In order to mesh gears on the splined main shaft with appropriate gears on the layshaft for obtaining different speeds, they are moved to the right or left. It derives its name from the fact that the meshing of the gears takes place by sliding of gears on each other.

A three speed sliding mesh gear-box is shown in Figure. Splines are provided on the main shaft. For meshing the pinions with the matching gears on the layshaft, the pinions are slided along the spline. When the main shaft is driven from the layshaft the gear reduction is provided by the first pair of gears which are always in mesh. They are usually known as constant mesh gears. For changing gear the clutch is depressed and the gear lever is moved till the selector pinion on the main shaft engages with its mating gear on the layshaft. The drive from the engine will be again transmitted through the gear-box when the clutch is released. To obtain three forward speeds, reverse and neutral, the relative position of the gears will be as below:

First gear: The largest gear on the main shaft is driven by the smallest gear or pinion on the layshaft. With corresponding increase torque, the speed reduction is quite high. When climbing and moving off steep hill, starting the vehicle from rest this gear is usually used.

Second gear: In this gear, there is less speed reduction and smaller torque increase.

Third or top gear: In order to revolve primary or main shaft at the same speed without any charge in the torque the main shaft is driven through a dog clutch in this gear.

Reverse: In this gear, the peed reduction is usually same as that in the first gear. But the direction of rotation of the main shaft will be reversed by introducing an idler in it. It is due to this change in the direction of rotation of the driving wheels provided by the idler that the motor vehicle moves in reverse direction.

TWO-STROKE TRACTOR ENGINES

Two-stroke tractor engines are invariably of the compression-ignition type. Some small cultivators have two-stroke spark-ignition engines also.

In the two-stroke cycle each downward stroke of the piston is first a power stroke and then an exhaust stroke, and each upward stroke of the piston provides for replenishment of the air charge as well as its subsequent compression. The air for combustion assists removal of the exhaust gases; it is therefore known as 'scavenge' air, and its admission to the engine as 'scavenging’. For efficient scavenging a supply of air is required at a pressure above atmospheric; this can be secured by provision of a 'blower' or by adapting the engine crankcase as an air pump ('crankcase compression scavenging'). A two-stroke engine with a rotary blower of lobed type is shown in Figure 4; in this design exhaust valves are used in the cylinder head, so that the advantages of 'uniflow' scavenging are obtained - i.e. the incoming air sweeps the spent charge out of the cylinder in a generally uniform direction, with relatively little intermixing between the two.

Crankcase-compression scavenging is employed in the exceptionally simple single-cylinder 'valveless' engines of which considerable numbers have been built. An example is shown in Figure 5, and the sequence of events in an engine of this kind is shown in the lower diagram in Figure 6. On the compression stroke of the piston, air is inducted into the crankcase through a non-return valve. On the power stroke the air in the crankcase is compressed to a pressure slightly (perhaps 2 lb./sq.in.) over atmospheric. Near the end of this stroke the piston uncovers an exhaust port in one side of the cylinder wall, and then a 'transfer port' in the other, communicating with the crankcase; the top of the piston (the 'piston crown') is so shaped that the air thus entering the cylinder takes a path promoting scavenging and sweeps residual burnt gases out through the exhaust port. As the piston begins the next stroke it covers both ports and a new cycle follows.

FORK LIFTS & LIFT TRUCKS

Fork lifts and lift trucks serve the same purpose in that they transport goods, materials, etc., from one place to another and stack them ready for storage, or load them onto trucks, box cars, etc. On the other hand, a lift truck is designed to operate in rough terrain and has as its power source a conventional wheel tractor. Fork lifts are also self‑propelled machines, but they have smaller wheels which are about 10 to 14 in [25.4 to 35.56cm] in diameter and are of a solid rubber design. The lift capacity and lift height of lift trucks is greater than that of the fork lift. Fork lifts are pow­ered by air‑cooled gasoline or petroleum gas engines or some are battery‑powered, while the larger lift trucks use diesel engines exclusively. However, when the unit has to operate inside buildings they employ petroleum gas engines or battery power to drive the wheel motor and the hydraulic pump. Fork lifts are commonly driven hydrostatically or by electric wheel motors, whereas lift trucks use standard transmissions, power-shift transmissions, or are hydrostatically driven. Four‑speed forward and reverse ranges are used in the standard or power-shift transmissions.

The lift trucks are classified by their lift capacity and lift height. Their lift capacity range is between 1400 and 120,000 lb [65.6 and 54,480 kg]. The lift height range is between 9.6 and 42 ft [2‑9 and 12.81 m]. Depending on the lift capacity, either a conventional drive axle or a drive axle having planetary wheel hubs is used. The fork lift uses band brakes which are hydraulically applied, whereas lift trucks use drum brakes which may be applied hydraulically or by oil or air.

The lift of a fork lift and lift truck is similar in design and in turn, in operating principles. The major components are

• The lift frame

• The mast, consisting of the inner and outer mast

• The single‑acting lift cylinders

• The double‑acting tilt cylinders

• The carriage with the forks

The lift frame is mounted to the tractor, and the outer mast is pivot‑fastened at the bottom to the lift frame. The two double‑acting tilt cylinders are fastened to the lift frame or tractor and the rod ends of the pistons are pivot‑fastened to the outer mast. The inner mast is guided by rollers in the channels of the outer mast. Carriage load rollers and carriage thrust rollers are fastened to the carriage frame to support the carriage and guide it through the inner mast. The lift cylinder is fastened to the lower mast cross member, and the piston rod end is pivot‑fastened to the inner mast cross member (crosshead shaft). The ends of the two lift chains are fastened to the sides of the lift cylinders and placed over guide rollers which are bearing‑supported by the crosshead shaft. The other ends of the lift chains are fastened to the bottom of the carrier frame. The two forks are positioned on the shaft and supported in the bores of the carrier frame, and the lower ends of the forks rest against the lower cross frames.

LIFT OPERATION

Before driving the forks under the pallet or positioning them over the load, the operator must first operate the directional control valve to direct oil to the tilt cylinders, either into the piston ends or into the rod ends of the cylinders, to tilt the mast to a suitable fork position. At the same time the lift cylinder directional control valve must be operated to direct oil into or from the lift cylinders to raise or lower the forks. When raising the load, the piston is forced upward, raising the inner mast. Since the lift chains are fastened to the upper end of the lift cylinder piston, and on the bottom to the carriage frame, the extension of the inner mast raises the carriage frame by this extended distance because the chain is shortened. To lower the load, the directional control valve position is reversed, allowing the oil to flow from the lift cylinder to the directional control valve and back to the reservoir. This removes the force from the piston and the weight, lowering the piston, the inner mast, and the carriage.

VACUUM SERVO BRAKES

When the vacuum is obtained from the manifold of the engine or a separately driven exhauster used to assist the braking effort the system is called vacuum servo-brakes.  The system consists of a vacuum reservoir connected through a non-return valve to the inlet mani­fold of the engine.  Two connections from vacuum reservoir, one on each side of the piston of the servo cylinder is provided; on left side the connection is through the control unit where as right side is connected directly.  The piston of the servo cylinder' is further connected to the piston of the boost cylinder or the brake linkage.  The control unit consists of a piston to which two valves are attached.  The lower valve controls the connection between the reservoir and the right side of the servo cylinder piston.  The upper valve controls the connection between the atmosphere and the left side of the servo cylinder piston.  The other side of the piston of the control unit is actuated by the pedal effort through a master cylinder.

When the brake pedal is at off position then the lower value is opened and the upper valve is closed.  Under this position the air from the atmosphere is disconnected and the vacuum from reservoir is created on both the sides of the piston of the servo cylinder.  When the brake pedal is depressed the brake fluid pushes the piston in the control unit.  This action closes the lower valve and opens the upper valve of the control unit, thereby -exposing the left side of the servo cylinder piston to atmospheric pressure and acting the vacuum on the right side.  This action of the vacuum in the right side of the servo piston moves it to the right thereby utilizing this movement through the mechanical or hydraulic means to the wheel cylinders and applying the brakes.  In this way the driver effort is utilized to control the positions of valves of the control unit and the vacuum effort is applied for braking through the booster unit.

MULTI PLATE CLUTCH

The clutch having more than three discs is referred as multi disc clutch or multi plate clutch. It is similar to single plate clutch but has more number of frictional and metallic plates. Due to the increase in the numbers of plates (friction) the frictional surface in contact is also increased which increases the capacity of the clutch to transmit the some torque the diameter of the plate clutch. Hence the clutches are mostly commonly in two wheelers and three wheelers due to compact in size. It is used in heavy duty transmission system for transmitting higher torque. (For example torque transmission in heavy earth moving equipments) and power take off (P. T. O.) transmission in tractors.

 

Construction: Construction of multi plate clutches is similar to single plate clutch except the arrangement of number of friction plates and metal plates. It consists of inner drum which is referred to clutch shaft and has a number of plates splined to the outer surface. Another drum is coupled to fly wheel and carries a number of plates splined to it inner surface. The plates are arranged in alternate manners. The plates can revolve with the drum as well as it can slide axially. A spring keeps the outer and inner plates pressed together, so that the driving members transmit the power to the driven member. The clutches can be disengaged by pulling the inner drum against the spring force.

      Multi plate clutch can be dry type or wet type. The clutch is partially filled with oil. The coefficient of friction in oil varies from 0.07 to 0.17 of asbestos based fabrics.

1. The oil acts as cushioning  medium to provide smooth engagement and disengagement
2. The oil also carries the heat dissipated by the clutch due to friction. This reduces operations temperature and increases the left of the clutch plates.
3. The oil acts as lubricant and reduces axial thrust lost due to bending on splines.

The major disadvantage is the reduction in coefficient of friction when immersed in oil. It can be compensated by using high operating pressure of different friction material. Generally cork inserted multi plate clutches are used in wet clutches. In wet clutches the fluid under pressure is fed along the shaft.

DIAPHRAGM CLUTCH

In this type of diagram type springs are used instead of coil / helical springs. This type of clutch does not require any release levers as the spring itself acts as the series of levers. This type of springs do not have constant rate characteristics as in the case of coil springs and the pressure on the diaphragm springs increases until it is in flat position, thereafter decreases after passing this position. Hence the driver does not have to exert heavy pedal pressure to hold the clutch out of engagement compared to coil spring type. In coil spring type the spring pressure increases when the pedal is depressed to disengage the clutch and high pressure is required to keep the clutch in disengaged position.

This clutch consists of conventional friction clutch, thrust plate, diaphragm type spring and release sleeve. The diaphragm is held between the inner end of the main bearing and its outer circumstance fits into the counter bore of the thrust plate. The central position of the diaphragm spring is divided into several segments by radial slots terminating into holes. These segments acts like spring providing the required thrust on the pressure plate. This simple arrangement eliminates the necessity for providing separate release levers.

Working:  In the engaged position the spring pivots on the inner pivot rings as it is held on the clutch cover so that its outer rings contacts with the pressure plate. Again in this conical position the spring exerts through pressure to keep the pressure plate in firm contact with the clutch plate and flywheel. When the pedal is depressed the linkage moves release bearing toward the flywheel. When the pedal is depressed the linkage moves release bearing towards the flywheel to disengage the clutch. As the bearing contacts with inner position of the conical springs it moves that position forward which cause the link to move backward. This removes the pressure on the pressure plate and release the clutch plate from contact with other driving members.

Another type of conical spring used is the crown spring. This type differs from the tapered finger type with its surface corrugated instead of flat and the centre section is continuous without any spring. The clutch spring fits between the pressure plate and clutch cover. The entire assembly is held together by six spring retainer located on the pressure plate. The actuation of this type of spring is similar to integral / split type diaphragm spring

SINGLE PLATE CLUTCH

Driving Members:  Driving members of single plate clutch are input shaft (crank shaft) fixed to the flywheel, pressure plate, and the clutch cover which is bolted to the flywheel. These fly components rotate along with the crank shaft in both engaged and disengaged condition. Fly wheel is attached to the crank shaft and has threaded bolts or holes or grooves for bolting the clutch covers. Machined surface of the flywheel contacts the clutch facing. The pressure plate applies the required force on the clutch plate which contacts with fly wheel.

To apply the required force pressure springs are attached between the pressure plate and clutch cover. Pressure plate can be withdrawn by releasing the spring with the help of release lever. Lugs are provided on the pressure plate for providing the release fingers. Pressure plate springs are provided inside, release finger, and anti-ratting springs are provided inside the clutch cover and the entire assembly is bolted to fly wheel.

Driven members: It is the clutch plate which is splined to the driven shaft (clutch shaft or input shaft of gear box) clutch plate is used with friction material on both the surfaces. It consists of a centre hub with internal splines which moves along the splined shaft during the transmission. The power is transmitted from the clutch to the shaft through these splines. It consists of torsional or cushioning springs which transmit the force applied to the facing to the central hub. The spring also reduces torsional vibrations and provides smooth engagement or disengagement of the clutch. The friction material is normally riveted to the projected portions of the clutch disc in CMVS and HMVS.

Actuating members: It consists of release fingers, withdrawal fork and release bearing. The outer end of the release finger is located on the pressure plate and inner end is projected towards the clutch shaft and are positioned with the help of anti-rattling springs. Withdrawal fork carrying the release bearing is pivoted in the clutch outer casing. The release bearing actuates the inner end of the release fingers.  

In fully engaged condition the driven plate is firmly clamped between the flywheel and pressure plate due to the force applied by springs. This forms a non-slip connection between the driving and driven plates. Hence when the flywheel rotates the clutch plate also rotates and this cause the transmission of power to the input shaft of gear box through splines. When clutch pedal is depressed the pressure on the driven plate is released by compressing the pressure springs through the release fingers. In this condition there is no force acting on the clutch plate and is free between the flywheel and pressure plate. This disengaged condition ensures easier shifting of gears. 

AIR SUSPENSION

Air suspension systems are becoming increasingly popular because of certain advantages they possess over the conventional metal springs. These are

1. A variable space for wheel deflection is put to optimum use by virtue of the automatic control devices.
2. Since the vehicle altitude remains constant, the changes in head lamp alignment due to varying load are avoided.
3. The spring rate varies much less between the laden and un-laden conditions, as compared that of that of conventional leaf springs, reducing the dynamic loading.
4. The improved standard of ride comfort and noise reduction attained by the use of air springs reduces both driver and passenger fatigue.

In the lay out shown the four air springs are mounted in the same positions where generally the coil springs are mounted. An air compressor takes the atmospheric air though an air filter and compresses it to a pressure of about 240 Mpa. The same pressure is maintained in the accumulator tank, which is provided by a safety relief valve. This high pressure air goes through the lift control valve and the leveling valves to the air springs as shown. The lift control valve is operated manually by means of a handle on the control panel through a cable running from the valve to the handle. The initial height is adjusted according to the loading conditions.

TORSION BAR SPRING

A torsion bar spring, usually called as a torsion bar is a spring steel rod that uses its torsional elasticity to resist twisting and takes only the shear stresses. One end of the torsion bar is anchored to the frame or other structural member of the body and the other end to a component that is subjected to torsional load.

The amount of energy stored per unit weight of material is nearly the same as that of the coil spring. Torsion bar is oftenly used with the independent suspension. As shown in the figure, the bar is fixed at one end to the frame, while the other end is fixed to the end of the wheel arm and supported in the bearing. The other end of the wheel arm is connected to the wheel hub. When the wheel strikes a bump, it start vibrating up and down, thus exerting torque on the torsion bar, which acts as a spring.

Torsion bar is lighter as compared to the leaf springs and so it occupies less space. As the torsion tubes are much stiffer than the bars, it is preferred. The main disadvantage of the torsion bar is that it does not take the braking or driving thrust so that additional linkages has to be provided for this purposes. The second disadvantage is that the absence of friction force to damp out the vibrations and hence additional dampers are to be provided.

LEAF SPRING


Leaf springs are made up of a number of curved bands of spring steel called leaves sticking together in order from shortest to longest. This stack of leaves is fastened together at the center with a center bolt or U- bolt to prevent the longitudinal movement. Similarly sometimes the leaves are made with pips or projections at the bottom and recess at the top surface. The leaves are arranged in such a way that the projection of the upper spring should mesh in the recess of the lower spring. Also to keep the leaves from slipping out of place, they are held at several places with the clips. Both ends of the longest or main leaves are bent to form spring eyes, used to attach the spring to the frame. 

To adjust the variations in length of the master leaf while the vehicle move across the road irregularities, one end of the spring is connected to the fame through a shackle and the other end is mounted directly on the frame with a pin. For the front suspension, it is a usual practice to provide the shackle in the front side of the spring to reduce the wheel wobble.

Generally, the longer a leaf spring, the softer it will be. Also the more leaves in a leaf spring, the greater the load they will withstand. But on the other hand as the spring will become firmer, the riding comfort will suffer.

The curvature of each leaf is called a nip. As the nip of the leaf is greater, shorter the leaf will be. Each leaf curves sharply than the one above the stack. When the center bolt is tightened, the leaves flatten somewhat and causing the ends of the leaves to press very lightly against one other.

The suitable steels that have been used for the manufacture of leaf springs are chrome-vanadium steel        (C-0.46%, Cr-1.4%, Va-0.18%), silico-manganese steel (C-0.52%, Si-1.95%, Mn-1.05%) and carbon steel (C-0.55%, Mn-0.6%, Si-0.2%).

Types of leaf spring:         

a)  Semi-elliptic type spring  

b)  Quarter elliptic spring   

c)  Transverse type       

d)  Helper springs

The semi-elliptic type leaf spring is the most common type in use where, the spring is attached to the frame at its middle to the axle. One end is connected through a shackle and the other end is connected to the frame through a pin.The quarter elliptic type spring is a cantilever type spring, which is pivoted at its one end and the other end is shackled or pivoted to the axle. The short leaves in this type of springs are arranged in at the top. This type is not in common use now.

Transverse type spring is arranged transversely to the vehicle or parallel to the axle. This spring is rigidly bolted to the frame at its center. Both the ends of the spring are connected to the axle through the shackles. The disadvantage in using this type of spring is that the vehicle tends to roll at the turns since the frame is clamped only to their centers.

The helper springs or auxiliary springs are provided in addition to the main leaf springs when the vehicle is meant to carry heavy loads. This will allow a wide range of loading. Helper springs are an additional set of leaf springs clamped with the same U– bolt on the top of the main spring. Generally the helper springs are used in the rear side only. When the vehicle is lightly loaded, these helper springs will not take any loads and will come in action and share the loads only after certain deflection of the main leaves.

COMMON RAIL DIRECT INJECTION   [CRDI]

In CRDI, we have sensors for engine speed, air mass flow, crank speed, cam shaft position, turbo air boost pressure, fuel rail pressure, air temperature, coolant temperature, accelerator pedal position etc.Thus it is clear that the functioning of all electronically controlled fuel control systems depends on the inputs from different types of sensors. The ECU (Electronic Control Unit) receives these signals from sensors and after manipulation and calculations sends outputs to vary the injection timing, fuel quantity, ignition timing etc and also to control systems like the fuel injection pump, idle speed control unit, particulate trap regenerator (in a diesel engine), coolant supply etc.

GADGETS FROM HP

MediaSmart Receiver x280

NHewlett-Packard continues to emphasize both traditional PC technology along with newer, crossover consumer electronics--all of which center around the explosion of media in the home. The latestinnovation: The $300 HP MediaSmart Receiver x280N, which streams music, photos, and video from one (or several) Windows systems to any HDTV, in HP's bid for a piece of the digital media adapter pie. This media streaming box works as a Windows Media Center Extender; it also has an HP Pocket Media Drive bay and two USB ports, so you can also store and access content without streaming from a PC. The unit connects via ethernet and 802.11 a/b/g/n; and has HDMI (up to 1080p), component video, and digital audio outputs

MediaSmart TVs Get Smarter

HP may not be the first name you think of for TVs, but the company is the first with connected TVs. HP has refreshed its MediaSmart TVs: All models are now 1080p, connect via ethernet and 802.11 a/b/g/n, and have built-in extenders for Microsoft's Windows Media Center (you can access multiple online services via this connectivity, including downloading movies from CinemaNow). The included remote control can handle up to four entertainment devices; the TVs now have three HDMI ports. The 42-inch SL4282N will sell for $1900; and the 47-inch SL4782N will sell for $2400.

Data Saver: New MediaVault 

The HP MediaVault line gets a much-needed boost with this user-expandable storage system. The mv2100 and mv5100 series are aimed at homes and small businesses, respectively (the ormer, a two-bay unit, tops out at 500GB; the latter--a multibay unit referred to as the Media Vault Pro--comes in 1TB and 1.5TB versions). The Linux-based network-attached storage devices pack a Marvell processor for improved performance, and both models borrow features from HP's MediaSmart server (such as securely sharing images via Photo WebShare and easily accessing music via iTunes server).

$1000 PC Packs Blu-ray, Too

Not so long ago, Blu-ray Disc playback was a premium feature on a PC. The HP Pavilion Slimline s3330f PC--the most interesting of HP's three PC announcements here at the Consumer Electronics Show-- comes in at under $1000, and delivers a dual-format Blu-ray Disc and HD DVD drive (which might be useful for those of you with HD DVDs lying around). The space-saving s3330f is notably slim--HP says it's a third of the size of an ordinary PC tower. Even so, this model still manages to squeeze in a Pocket Media Drive bay. The unit also comes with a digital TV tuner, plus an Nvidia GeForce 8500 card with HDMI out.

Amped-Up Mobile Graphics

The HP Pavilion HDX series notebook gains a major upgrade: The option of integrating 512 MB Nvidia GeForce 8800M GTS graphics. This top-of-the-line mobile chipset from Nvidia--announced in late November 2007--should provide significantly better frame rates for gameplay, to the point that previously unplayable games may now be enjoyed in a notebook PC (Alienware has already announced it will use this chipset in notebooks due out this quarter). Another first: The HDx now has a 20.1-inch WUXGA XHD Ultra Brightview display. Plus, this model also now supports both Blu-ray and HD DVD.

 Monitors Add HDMI

HP's two new monitors, the 22-inch w2207h and the 24-inch w2408h continue the trend towards high-def by adding HDMI connections (in lieu of DVI; VGA remains). Pictured above, the 24-inch w2408h Vivid Color monitor should boast improved image performance over previous models, according to HP.