2 .FORMACIÓN Y FABRICACIÓN DE CABLES
2.11 PARTES DE UNA GRÚA TIPO TORRE
The “pin”
The “skewer”
Two attacks at once
What is a “tactic?” A tactic is a sequence of moves, at most a few moves long, played with some goal in mind. The most dramatic tactics have the goal either of checkmate, or of winning material. In this chapter and the next, I’ll show you some of the most important tactics for winning material. Of course no two positions are exactly alike, but you’ll see that there are some typical tactics that fall into patterns you can
recognize in many different positions. Once you learn these patterns, you’ll be able to anticipate them from your opponent, and you’ll be able to use them to your advantage.
The Fork
When one piece attacks two pieces at the same time, it’s called a fork. I’ll show you examples of forks by each different piece. Let’s start with the pawn.
Pawn Forks
Consider Diagram 1. It’s White’s turn to move. Black is threatening to capture the pawn on e4, so White could defend it with 1.Bd3, or exchange pawns with 1.exd5 exd5. But White has a much better move: 1.e5! White attacks both Black’s bishop on d6 and knight on f6. There is no way Black can defend both of them. He must lose a
bishop or a knight for a pawn, as is illustrated in Diagram 2.
Chess Talk
A tactic is a sequence of moves played to accomplish some goal, often winning material or giving checkmate.
The paradox of the pawn fork is that pawn forks are so dangerous precisely because pawns are worth so much less than the other pieces. It’s useless to protect a piece against a pawn, because if you lose even a knight or a bishop for a pawn, you’ve lost a lot of material.
In fact, it’s often worth a pawn to set up a pawn fork. Take a look at Diagram 3.
It’s White’s turn. Notice that Black’s pawn on e5 is attacked twice by White’s pawn on d4 and knight on d3, and defended twice by Black’s knight on d7 and bishop on d6.
But if White could get one of his own pawns to e5, and if that pawn were protected, Black’s knight on f6 and bishop on d6 would be forked. Do you see a way to do that?
Diagram 1: White to move.
Diagram 2: White plays 1.e5! and forks Black’s knight and bishop.
Chess Talk
A fork is when one piece attacks two pieces at the same time.
White cleverly plays 1.f4! (see Diagram 4), which attacks the pawn on e5. Since it’s attacked by two pawns, it’s useless to defend it with a piece, and there is no way to defend it with a pawn. Unless Black wants to lose a whole pawn for nothing, Black had better capture one of White’s pawns. So in Diagram 5 Black plays 1 . . .exd4.
But now White can carry out his plan to establish the pawn fork by playing 2.e5 (see Diagram 6). White has lost a pawn, but he’s attacking two pieces and will win one of them for a pawn, so he’ll come out ahead a piece for two pawns.
Diagram 3: White to move.
Diagram 4: White plays 1.f4!
Diagram 5: Black plays 1 . . .exd4.
Diagram 6: White plays 2.e5, forking Black’s knight and bishop.
Knight Forks
Knights strike terror into the hearts of the rooks and the queen, because they’re so tricky. Two pieces that seem to be far apart and out of range of anything can suddenly find themselves forked by a knight. Watch out for these guys!
Consider Diagram 7, where it’s White’s turn. What danger could there possibly be to Black in this position? All the danger in the world after 1.Ne4, as you can see in Diagram 8. Both Black’s queen and rook are attacked by the knight, and Black has no way to remove the threat to both pieces in his next turn, so he must lose material. By the way, Black should make the best of a bad deal by moving the queen to a square where it can recapture the knight once it captures the rook on c5. For example, 1. . .Qe7 is a good move.
Part of the danger of knights is that because they don’t move like any other piece, when they fork two (or more) pieces, they often do not have to be defended. (Compare to the pawn fork in Diagram 2, for example.) Diagram 9 shows the most deadly knight fork of all: the “family fork,” so-called because the knight forks both the king and queen.
Black is in check, so he must move the king, and White will win a whole queen!
Diagram 7: White to move.
In fact, this brings us to an important point. Why would you want to promote a pawn to anything other than a queen? The most common reason is to promote to a knight to set up a family fork. Promote to a queen, and you just gain a queen. Promote to a knight while setting up a family fork at the same time, and you gain a knight, plus you capture a queen. Diagrams 10 and 11 demonstrate this.
Diagram 8: White plays 1.Ne4!, forking the rook and queen.
Diagram 9: White’s knight forks Black’s king and queen.
Diagram 10: Black to move.
Diagram 11: Black plays 1 . . .e1=N+, forking the king and queen.
Bishop Forks
The other pieces may not be quite as dangerous forkers as the pawn and the knight, but they are not to be trifled with! Consider Diagram 12. It’s White’s move, but Black has a material advantage of a knight, rook, and pawn. How much damage could White possibly do?
Lots! White starts with 1.Bxc6+ (see Diagram 13), which not only captures a knight, but also forks Black’s rook on d5 and king on e8. Black responds with 1 . . .Ke7.
Maybe Black figures that even after losing the knight and the rook, he will still have a material advantage of a pawn.
Chess Talk
When a knight forks the king and the queen, it’s called a family fork.
But Black doesn’t notice that after 2.Bxd5, White is again forking two pieces: the
knight on g8 and the rook on b3 (see Diagram 14). Black must lose one or the other, which will leave White with the large advantage of a bishop for a pawn. Notice that Black’s pawns on b6 and g7 are getting in his way. If Black didn’t have the pawn on b6, he could play 2 . . .Rb8 to move the rook out of the attack and also protect the knight. If Black didn’t have the pawn on g7, then if he played 2 . . .Rg3 he would move the rook out of the attack and also protect the knight at the same time. But the pawn on b6 prohibits 2 . . .Rb8, and the pawn on g7 blocks the g-file, so that 2 . . .Rg3 doesn’t protect the knight. What a bishop!
Blunders
It’s good to be aggressive when you play, but you should never make an attack without taking into account how your opponent might respond.
Diagram 12: White to move.
Diagram 13: White plays 1.Bxc6+.
Diagram 14: Black plays 1 . . .Ke7 and White plays 2.Bxd5.
Rook Forks
Whenever you see two pieces along the same file or the same rank, and a rook nearby, watch out! There may be a fork just waiting to happen.
Consider Diagram 15. Material is just about equal. In a game between two
grandmasters, a draw would be the most likely result. However, in this case Black isn’t satisfied with a draw, so to be aggressive, Black plays 1 . . .Ne2?? (see Diagram 16) to attack the rook.
Diagram 15: Black to move.
Diagram 16: Black plays 1 . . .Ne2??.
But this is a horrible blunder! Notice how Black has carelessly put the knight into the same file as the king without considering the consequences. White snatches the
opportunity to fork the two pieces by playing 2.Re3+. Black must get out off check, and then White captures the knight (see Diagram 17) in the next move, leaving Black with a lost position.
Diagrams 18 and 19 give another example of a rook fork. Here Black even has a
material advantage, but it will not last. White plays 1.Rd7!, and attacks both the knight on e7 and the bishop on b7. One or the other must go: The fork will give White a winning material advantage.
Diagram 17: White plays 2.Re3+, forking king and knight.
Diagram 18: White to move.
Diagram 19: White plays 1.Rd7!, forking knight and bishop.
Queen Forks
You can never be too careful with the queen. When thinking about your opponent’s queen, always check twice to make sure that there is not a fork hiding somewhere. And when thinking about your own queen, look to see whether an opportunity for a queen fork might be present. Because the queen combines the power of the rook and the bishop, it can attack two or more pieces from almost any square on the board.
Diagrams 20 through 22 show one example of how the ability of the queen to combine the rook’s move and the bishop’s move makes it such a dangerous piece. Black
decides to play 1 . . .Ng5??, but this is a grave error. White spots the flaw and plays 2.Qd8+! forking the king and the knight. Black must defend against the check, for example, by 2 . . .Kh7, and then White wins a knight for free by 3.Qxg5.
Here’s another example. In Diagram 23, Black wants to move the bishop. A good move would be 1 . . .Be6, which puts the bishop on the sensitive diagonal in front of the king on g8. But Black plays 1 . . .Bb7?? (see Diagram 24), a terrible mistake.
White pounces on the error by playing 2.Qb3+! (see Diagram 25), forking the bishop and the king. Black must defend against the check, which will leave the bishop
defenseless to the queen. (Notice that blocking the check with the bishop by playing 2 . . .Bd5 fails to save the bishop, because White can safely capture the bishop on that square with the pawn, knight, or queen.)
Diagram 20: Black to move.
Diagram 21: Black plays 1 . . .Ng5??.
Diagram 22: White plays 2.Qd8+, forking the king and knight.
King Forks
Because the king is so vulnerable, it’s unusual for the king to be used aggressively before many pieces have been exchanged, so it is not common for the king to fork pieces or pawns. But it can happen, just the same!
Consider Diagram 26. Black notices that his rook is attacked by the knight on g4, so he should move the rook away from the attack. Where should it go?
Diagram 23: Black to move.
Diagram 24: Black plays 1 . . .Bb7??
Diagram 25: White plays 2.Qb3+!, forking king and bishop.
A good move would be 1 . . .Re7, but Black tries to be too aggressive. He figures if he can give a check, why not do it? So Black plays 1 . . .Rg3+? (see Diagram 27), and only after 2.Kf2! does he realize that his rook and knight are forked by the king (see Diagram 28). The best Black can do is to play 2 . . .Rxg4, but after 3.Rxg4, Black has lost the exchange (rook for knight).
Blunders
There’s a saying in chess: “Patzer see a check, patzer give a check.” (A
“patzer” is a weak player.) It’s good to be aggressive, but don’t just give a check because you can: Make sure you take your opponent’s response into account.
A more typical king fork occurs when there are very few pieces left. Then it’s safer for the king to be used aggressively, and it will sometimes fork pawns. In Diagram 29, Black’s king has managed to make it all the way behind White’s pawns. Now Black reaps the benefits by playing 1 . . .Kb2! (in Diagram 30), which attacks three pawns at the same time. Now that’s a fork fit for a king! (See Chapter 14 for more about how the king can be used aggressively when there are only a few pieces left on the board.) Diagram 26: Black to move.
Diagram 27: Black plays 1 . . .Rg3+?.
Diagram 28: White plays 2.Kf2!, not only removing the king from check, but also forking Black’s rook and knight.
Patrick’s Pointers
The king does not like to be exposed along a rank, file, or diagonal!
Among the many dangers of being so exposed is that there might be a fork lurking. And a fork that involves the king is doubly dangerous: Since the king must be protected at all costs, the other piece that is forked is often helpless. So if you notice that your opponent’s king is exposed along an open rank, file, or diagonal, look for a way to take advantage of it. And if your own king is so exposed, try to get it out of harm’s way.
Diagram 29: Black to move.
Diagram 30: Black plays 1 . . .Kb2!, forking all three of White’s pawns.
The Pin
When you attack a piece, and that piece cannot move without exposing another piece behind it to capture, you are pinning the first piece to the piece behind it. Only the long-range pieces—the bishop, the rook, and the queen—can pin one piece to another.
The ability to pin one piece to another is part of what makes those long-range pieces so dangerous!
I’ll show you some common ways for bishops, rooks, and queens to pin pieces. But keep this in mind: There’s a difference between pinning a piece to any ordinary piece, and pinning a piece to the king. When a piece is pinned to the king, the pinned piece can never move (because that would be moving into check). Therefore, pinning a piece to the king is especially effective for the player doing the pinning—and
dangerous for the player being pinned! In contrast, if a piece is pinned to an ordinary piece, you should always remember that it’s legal, though often undesirable, to move the piece.
Chess Talk
When one piece is attacked, and it can’t move without exposing a piece behind it to attack, the first piece is pinned to the piece behind it.
What should you do if your opponent is pinning one of your pieces and you want to
remove the pin? There are four ways to “break” a pin:
1. Capture the piece that is doing the pinning.
2. Attack the piece that is doing the pinning, and force it to move away.
3. Block the pin: Either put something between the pinning piece and the piece that is pinned, or put something between the pinned piece and the piece it’s pinned to.
4. Get out of the way: If all else fails, you can move the piece “behind” the pinned piece out of the line of fire.
Patrick’s Pointers
The fork is not always an automatic winner. When you use more valuable pieces to fork, you must watch out for the possibility that one piece may be able to move out of the attack and simultaneously protect the other piece. (Remember, the reason that pawn forks are so deadly is that it’s impossible to protect a piece from a pawn, since the piece is worth so much more than the pawn.)
Bishop Pins
The position in Diagram 31 is the position from Exercise #20 in the last chapter. The bishop on f5 pins the rook on g6 to the king. Black cannot move the rook from attack, because that would expose the king to check. So White will win the rook for the bishop.
When a piece is pinned to your opponent’s king, sometimes it’s better not to capture it right away, but to bring another piece over to help in the attack. That way, you can win the pinned piece without allowing your opponent to recapture the piece that captured it. Or, alternatively, you can capture the pinned piece with a piece of lower value than the one you are pinning it with.
The next few Diagrams illustrate what I mean. It’s Black’s move in Diagram 32. Black can only hope that White would be so foolish as to capture the rook right away with the bishop—then Black would recapture the bishop, and material would be equal. But Black realizes the real danger is that White might play 1.Ne5!, attacking the rook again, so that White can win it for nothing. It’s Black’s move, and he plays 1 . . .Nd5
(Diagram 33). Black’s idea is that if White plays 2.Ne5, Black can play 2 . . .Ne7, defending the rook and even attacking the bishop, thereby gaining time to remove the king from the pin while still protecting the rook by playing 3 . . .h5 and 4 . . .Kh6.
Diagram 31: White’s bishop pins Black’s rook to the king.
Diagram 32: Black to move.
Diagram 33: Black plays 1 . . .Nd5.
It’s a good plan, but it fails, because White plays 2.h5! in Diagram 34, attacking the rook with a pawn. There is nothing for Black to do. If Black plays 2 . . .Ne7 (see Diagram 35), then White plays 3.hxg6+, and if Black is so foolish as to recapture the pawn with 3 . . .Nxg6? (see Diagram 36), White will play 4.Ne5, winning the knight as well. What a pin!
Diagram 34: White plays 2.h5!, attacking the pinned rook with the pawn.
Diagram 35: Black plays 2 . . .Ne7, and White plays 3.hxg6+.
Diagram 36: If Black plays 3 . . .Nxg6?, White wins the knight by playing 4.Ne5.
Diagrams 37 and 38 show something else to watch out for. Suppose you pin your opponent’s rook to his queen with your bishop. Make sure that the rook can’t move away and give check at the same time, especially if your bishop isn’t protected! This is really a version of “two attacks at once,” which I will explain to you later in the chapter.
Diagram 37: Black to move.
Diagram 38: Black plays 1 . . .Rc2+!, and when White moves the king, Black will play 2 . . .Qxd5.
Finally, here are some typical pins: Bishop pinning knight to king (see Diagram 39), or queen (see Diagram 40). Notice that there is no reason for the side with the pinned knight to panic yet. Although there is a pin, there is no threat to win the pinned piece.
Even so, the bishop is often quite usefully employed in such a pin, because not only is the bishop being used actively, it’s also cutting down the effectiveness of the knight.
Diagram 39: Bishop pinning knight to king.
Diagram 40: Bishop pinning knight to queen.
Rook Pins
Diagrams 41–43 show some examples of rook pins. Notice in Diagram 43 that if the rook is going to pin the queen, it had better be protected! (The same holds true for a bishop pinning the queen, of course.)
One of the most common uses of the rook pin is to pin a piece to the uncastled king along the open e-file, if one side has castled early and the other side has not. (By the way, this is one very good reason to castle early!) Diagrams 44 and 45 show you what I mean. In Diagram 44, White has castled, and Black has not. Black’s knight and king are precariously placed on the same file! In Diagram 45, Black pays the price. White attacks the knight, which cannot move because it is pinned. Even if Black defends the knight, it can’t be saved, because next move White will attack the knight with a pawn, and the knight will have to stand his post while he is slaughtered by the pawn. Don’t let this happen to you!
Diagram 41: White’s rook pins Black’s bishop to the king.
Diagram 42: Black’s rook pins White’s knight to the king.